// File: Address.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // Look for revert reason and bubble it up if present
        if (returndata.length > 0) {
            // The easiest way to bubble the revert reason is using memory via assembly
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}

// File: Context.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// File: ERC165.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)

pragma solidity ^0.8.0;

import './IERC165.sol';

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
  /**
   * @dev See {IERC165-supportsInterface}.
   */
  function supportsInterface(bytes4 interfaceId)
    public
    view
    virtual
    override
    returns (bool)
  {
    return interfaceId == type(IERC165).interfaceId;
  }
}

// File: ERC2981.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (token/common/ERC2981.sol)

pragma solidity ^0.8.0;

import './IERC2981.sol';
import './ERC165.sol';

/**
 * @dev Implementation of the NFT Royalty Standard, a standardized way to retrieve royalty payment information.
 *
 * Royalty information can be specified globally for all token ids via {_setDefaultRoyalty}, and/or individually for
 * specific token ids via {_setTokenRoyalty}. The latter takes precedence over the first.
 *
 * Royalty is specified as a fraction of sale price. {_feeDenominator} is overridable but defaults to 10000, meaning the
 * fee is specified in basis points by default.
 *
 * IMPORTANT: ERC-2981 only specifies a way to signal royalty information and does not enforce its payment. See
 * https://eips.ethereum.org/EIPS/eip-2981#optional-royalty-payments[Rationale] in the EIP. Marketplaces are expected to
 * voluntarily pay royalties together with sales, but note that this standard is not yet widely supported.
 *
 * _Available since v4.5._
 */
abstract contract ERC2981 is IERC2981, ERC165 {
  struct RoyaltyInfo {
    address receiver;
    uint96 royaltyFraction;
  }

  RoyaltyInfo private _defaultRoyaltyInfo;
  mapping(uint256 => RoyaltyInfo) private _tokenRoyaltyInfo;

  /**
   * @dev See {IERC165-supportsInterface}.
   */
  function supportsInterface(bytes4 interfaceId)
    public
    view
    virtual
    override(IERC165, ERC165)
    returns (bool)
  {
    return
      interfaceId == type(IERC2981).interfaceId ||
      super.supportsInterface(interfaceId);
  }

  /**
   * @inheritdoc IERC2981
   */
  function royaltyInfo(uint256 _tokenId, uint256 _salePrice)
    public
    view
    virtual
    override
    returns (address, uint256)
  {
    RoyaltyInfo memory royalty = _tokenRoyaltyInfo[_tokenId];

    if (royalty.receiver == address(0)) {
      royalty = _defaultRoyaltyInfo;
    }

    uint256 royaltyAmount = (_salePrice * royalty.royaltyFraction) /
      _feeDenominator();

    return (royalty.receiver, royaltyAmount);
  }

  /**
   * @dev The denominator with which to interpret the fee set in {_setTokenRoyalty} and {_setDefaultRoyalty} as a
   * fraction of the sale price. Defaults to 10000 so fees are expressed in basis points, but may be customized by an
   * override.
   */
  function _feeDenominator() internal pure virtual returns (uint96) {
    return 10000;
  }

  /**
   * @dev Sets the royalty information that all ids in this contract will default to.
   *
   * Requirements:
   *
   * - `receiver` cannot be the zero address.
   * - `feeNumerator` cannot be greater than the fee denominator.
   */
  function _setDefaultRoyalty(address receiver, uint96 feeNumerator)
    internal
    virtual
  {
    require(
      feeNumerator <= _feeDenominator(),
      'ERC2981: royalty fee will exceed salePrice'
    );
    require(receiver != address(0), 'ERC2981: invalid receiver');

    _defaultRoyaltyInfo = RoyaltyInfo(receiver, feeNumerator);
  }

  /**
   * @dev Removes default royalty information.
   */
  function _deleteDefaultRoyalty() internal virtual {
    delete _defaultRoyaltyInfo;
  }

  /**
   * @dev Sets the royalty information for a specific token id, overriding the global default.
   *
   * Requirements:
   *
   * - `receiver` cannot be the zero address.
   * - `feeNumerator` cannot be greater than the fee denominator.
   */
  function _setTokenRoyalty(
    uint256 tokenId,
    address receiver,
    uint96 feeNumerator
  ) internal virtual {
    require(
      feeNumerator <= _feeDenominator(),
      'ERC2981: royalty fee will exceed salePrice'
    );
    require(receiver != address(0), 'ERC2981: Invalid parameters');

    _tokenRoyaltyInfo[tokenId] = RoyaltyInfo(receiver, feeNumerator);
  }

  /**
   * @dev Resets royalty information for the token id back to the global default.
   */
  function _resetTokenRoyalty(uint256 tokenId) internal virtual {
    delete _tokenRoyaltyInfo[tokenId];
  }
}

// File: ERC721A.sol



// SPDX-License-Identifier: MIT
// ERC721A Contracts v4.2.0
// Creator: Chiru Labs

pragma solidity ^0.8.4;

import './IERC721A.sol';

/**
 * @dev Interface of ERC721 token receiver.
 */
interface ERC721A__IERC721Receiver {
  function onERC721Received(
    address operator,
    address from,
    uint256 tokenId,
    bytes calldata data
  ) external returns (bytes4);
}

/**
 * @title ERC721A
 *
 * @dev Implementation of the [ERC721](https://eips.ethereum.org/EIPS/eip-721)
 * Non-Fungible Token Standard, including the Metadata extension.
 * Optimized for lower gas during batch mints.
 *
 * Token IDs are minted in sequential order (e.g. 0, 1, 2, 3, ...)
 * starting from `_startTokenId()`.
 *
 * Assumptions:
 *
 * - An owner cannot have more than 2**64 - 1 (max value of uint64) of supply.
 * - The maximum token ID cannot exceed 2**256 - 1 (max value of uint256).
 */
contract ERC721A is IERC721A {
  // Reference type for token approval.
  struct TokenApprovalRef {
    address value;
  }

  // =============================================================
  //                           CONSTANTS
  // =============================================================

  // Mask of an entry in packed address data.
  uint256 private constant _BITMASK_ADDRESS_DATA_ENTRY = (1 << 64) - 1;

  // The bit position of `numberMinted` in packed address data.
  uint256 private constant _BITPOS_NUMBER_MINTED = 64;

  // The bit position of `numberBurned` in packed address data.
  uint256 private constant _BITPOS_NUMBER_BURNED = 128;

  // The bit position of `aux` in packed address data.
  uint256 private constant _BITPOS_AUX = 192;

  // Mask of all 256 bits in packed address data except the 64 bits for `aux`.
  uint256 private constant _BITMASK_AUX_COMPLEMENT = (1 << 192) - 1;

  // The bit position of `startTimestamp` in packed ownership.
  uint256 private constant _BITPOS_START_TIMESTAMP = 160;

  // The bit mask of the `burned` bit in packed ownership.
  uint256 private constant _BITMASK_BURNED = 1 << 224;

  // The bit position of the `nextInitialized` bit in packed ownership.
  uint256 private constant _BITPOS_NEXT_INITIALIZED = 225;

  // The bit mask of the `nextInitialized` bit in packed ownership.
  uint256 private constant _BITMASK_NEXT_INITIALIZED = 1 << 225;

  // The bit position of `extraData` in packed ownership.
  uint256 private constant _BITPOS_EXTRA_DATA = 232;

  // Mask of all 256 bits in a packed ownership except the 24 bits for `extraData`.
  uint256 private constant _BITMASK_EXTRA_DATA_COMPLEMENT = (1 << 232) - 1;

  // The mask of the lower 160 bits for addresses.
  uint256 private constant _BITMASK_ADDRESS = (1 << 160) - 1;

  // The maximum `quantity` that can be minted with {_mintERC2309}.
  // This limit is to prevent overflows on the address data entries.
  // For a limit of 5000, a total of 3.689e15 calls to {_mintERC2309}
  // is required to cause an overflow, which is unrealistic.
  uint256 private constant _MAX_MINT_ERC2309_QUANTITY_LIMIT = 5000;

  // The `Transfer` event signature is given by:
  // `keccak256(bytes("Transfer(address,address,uint256)"))`.
  bytes32 private constant _TRANSFER_EVENT_SIGNATURE =
    0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef;

  // =============================================================
  //                            STORAGE
  // =============================================================

  // The next token ID to be minted.
  uint256 private _currentIndex;

  // The number of tokens burned.
  uint256 private _burnCounter;

  // Token name
  string private _name;

  // Token symbol
  string private _symbol;

  // Mapping from token ID to ownership details
  // An empty struct value does not necessarily mean the token is unowned.
  // See {_packedOwnershipOf} implementation for details.
  //
  // Bits Layout:
  // - [0..159]   `addr`
  // - [160..223] `startTimestamp`
  // - [224]      `burned`
  // - [225]      `nextInitialized`
  // - [232..255] `extraData`
  mapping(uint256 => uint256) private _packedOwnerships;

  // Mapping owner address to address data.
  //
  // Bits Layout:
  // - [0..63]    `balance`
  // - [64..127]  `numberMinted`
  // - [128..191] `numberBurned`
  // - [192..255] `aux`
  mapping(address => uint256) private _packedAddressData;

  // Mapping from token ID to approved address.
  mapping(uint256 => TokenApprovalRef) private _tokenApprovals;

  // Mapping from owner to operator approvals
  mapping(address => mapping(address => bool)) private _operatorApprovals;

  // =============================================================
  //                          CONSTRUCTOR
  // =============================================================

  constructor(string memory name_, string memory symbol_) {
    _name = name_;
    _symbol = symbol_;
    _currentIndex = _startTokenId();
  }

  // =============================================================
  //                   TOKEN COUNTING OPERATIONS
  // =============================================================

  /**
   * @dev Returns the starting token ID.
   * To change the starting token ID, please override this function.
   */
  function _startTokenId() internal view virtual returns (uint256) {
    return 0;
  }

  /**
   * @dev Returns the next token ID to be minted.
   */
  function _nextTokenId() internal view virtual returns (uint256) {
    return _currentIndex;
  }

  /**
   * @dev Returns the total number of tokens in existence.
   * Burned tokens will reduce the count.
   * To get the total number of tokens minted, please see {_totalMinted}.
   */
  function totalSupply() public view virtual override returns (uint256) {
    // Counter underflow is impossible as _burnCounter cannot be incremented
    // more than `_currentIndex - _startTokenId()` times.
    unchecked {
      return _currentIndex - _burnCounter - _startTokenId();
    }
  }

  /**
   * @dev Returns the total amount of tokens minted in the contract.
   */
  function _totalMinted() internal view virtual returns (uint256) {
    // Counter underflow is impossible as `_currentIndex` does not decrement,
    // and it is initialized to `_startTokenId()`.
    unchecked {
      return _currentIndex - _startTokenId();
    }
  }

  /**
   * @dev Returns the total number of tokens burned.
   */
  function _totalBurned() internal view virtual returns (uint256) {
    return _burnCounter;
  }

  // =============================================================
  //                    ADDRESS DATA OPERATIONS
  // =============================================================

  /**
   * @dev Returns the number of tokens in `owner`'s account.
   */
  function balanceOf(address owner)
    public
    view
    virtual
    override
    returns (uint256)
  {
    if (owner == address(0)) revert BalanceQueryForZeroAddress();
    return _packedAddressData[owner] & _BITMASK_ADDRESS_DATA_ENTRY;
  }

  /**
   * Returns the number of tokens minted by `owner`.
   */
  function _numberMinted(address owner) internal view returns (uint256) {
    return
      (_packedAddressData[owner] >> _BITPOS_NUMBER_MINTED) &
      _BITMASK_ADDRESS_DATA_ENTRY;
  }

  /**
   * Returns the number of tokens burned by or on behalf of `owner`.
   */
  function _numberBurned(address owner) internal view returns (uint256) {
    return
      (_packedAddressData[owner] >> _BITPOS_NUMBER_BURNED) &
      _BITMASK_ADDRESS_DATA_ENTRY;
  }

  /**
   * Returns the auxiliary data for `owner`. (e.g. number of whitelist mint slots used).
   */
  function _getAux(address owner) internal view returns (uint64) {
    return uint64(_packedAddressData[owner] >> _BITPOS_AUX);
  }

  /**
   * Sets the auxiliary data for `owner`. (e.g. number of whitelist mint slots used).
   * If there are multiple variables, please pack them into a uint64.
   */
  function _setAux(address owner, uint64 aux) internal virtual {
    uint256 packed = _packedAddressData[owner];
    uint256 auxCasted;
    // Cast `aux` with assembly to avoid redundant masking.
    assembly {
      auxCasted := aux
    }
    packed = (packed & _BITMASK_AUX_COMPLEMENT) | (auxCasted << _BITPOS_AUX);
    _packedAddressData[owner] = packed;
  }

  // =============================================================
  //                            IERC165
  // =============================================================

  /**
   * @dev Returns true if this contract implements the interface defined by
   * `interfaceId`. See the corresponding
   * [EIP section](https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified)
   * to learn more about how these ids are created.
   *
   * This function call must use less than 30000 gas.
   */
  function supportsInterface(bytes4 interfaceId)
    public
    view
    virtual
    override
    returns (bool)
  {
    // The interface IDs are constants representing the first 4 bytes
    // of the XOR of all function selectors in the interface.
    // See: [ERC165](https://eips.ethereum.org/EIPS/eip-165)
    // (e.g. `bytes4(i.functionA.selector ^ i.functionB.selector ^ ...)`)
    return
      interfaceId == 0x01ffc9a7 || // ERC165 interface ID for ERC165.
      interfaceId == 0x80ac58cd || // ERC165 interface ID for ERC721.
      interfaceId == 0x5b5e139f; // ERC165 interface ID for ERC721Metadata.
  }

  // =============================================================
  //                        IERC721Metadata
  // =============================================================

  /**
   * @dev Returns the token collection name.
   */
  function name() public view virtual override returns (string memory) {
    return _name;
  }

  /**
   * @dev Returns the token collection symbol.
   */
  function symbol() public view virtual override returns (string memory) {
    return _symbol;
  }

  /**
   * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
   */
  function tokenURI(uint256 tokenId)
    public
    view
    virtual
    override
    returns (string memory)
  {
    if (!_exists(tokenId)) revert URIQueryForNonexistentToken();

    string memory baseURI = _baseURI();
    return
      bytes(baseURI).length != 0
        ? string(abi.encodePacked(baseURI, _toString(tokenId)))
        : '';
  }

  /**
   * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
   * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
   * by default, it can be overridden in child contracts.
   */
  function _baseURI() internal view virtual returns (string memory) {
    return '';
  }

  // =============================================================
  //                     OWNERSHIPS OPERATIONS
  // =============================================================

  /**
   * @dev Returns the owner of the `tokenId` token.
   *
   * Requirements:
   *
   * - `tokenId` must exist.
   */
  function ownerOf(uint256 tokenId)
    public
    view
    virtual
    override
    returns (address)
  {
    return address(uint160(_packedOwnershipOf(tokenId)));
  }

  /**
   * @dev Gas spent here starts off proportional to the maximum mint batch size.
   * It gradually moves to O(1) as tokens get transferred around over time.
   */
  function _ownershipOf(uint256 tokenId)
    internal
    view
    virtual
    returns (TokenOwnership memory)
  {
    return _unpackedOwnership(_packedOwnershipOf(tokenId));
  }

  /**
   * @dev Returns the unpacked `TokenOwnership` struct at `index`.
   */
  function _ownershipAt(uint256 index)
    internal
    view
    virtual
    returns (TokenOwnership memory)
  {
    return _unpackedOwnership(_packedOwnerships[index]);
  }

  /**
   * @dev Initializes the ownership slot minted at `index` for efficiency purposes.
   */
  function _initializeOwnershipAt(uint256 index) internal virtual {
    if (_packedOwnerships[index] == 0) {
      _packedOwnerships[index] = _packedOwnershipOf(index);
    }
  }

  /**
   * Returns the packed ownership data of `tokenId`.
   */
  function _packedOwnershipOf(uint256 tokenId) private view returns (uint256) {
    uint256 curr = tokenId;

    unchecked {
      if (_startTokenId() <= curr)
        if (curr < _currentIndex) {
          uint256 packed = _packedOwnerships[curr];
          // If not burned.
          if (packed & _BITMASK_BURNED == 0) {
            // Invariant:
            // There will always be an initialized ownership slot
            // (i.e. `ownership.addr != address(0) && ownership.burned == false`)
            // before an unintialized ownership slot
            // (i.e. `ownership.addr == address(0) && ownership.burned == false`)
            // Hence, `curr` will not underflow.
            //
            // We can directly compare the packed value.
            // If the address is zero, packed will be zero.
            while (packed == 0) {
              packed = _packedOwnerships[--curr];
            }
            return packed;
          }
        }
    }
    revert OwnerQueryForNonexistentToken();
  }

  /**
   * @dev Returns the unpacked `TokenOwnership` struct from `packed`.
   */
  function _unpackedOwnership(uint256 packed)
    private
    pure
    returns (TokenOwnership memory ownership)
  {
    ownership.addr = address(uint160(packed));
    ownership.startTimestamp = uint64(packed >> _BITPOS_START_TIMESTAMP);
    ownership.burned = packed & _BITMASK_BURNED != 0;
    ownership.extraData = uint24(packed >> _BITPOS_EXTRA_DATA);
  }

  /**
   * @dev Packs ownership data into a single uint256.
   */
  function _packOwnershipData(address owner, uint256 flags)
    private
    view
    returns (uint256 result)
  {
    assembly {
      // Mask `owner` to the lower 160 bits, in case the upper bits somehow aren't clean.
      owner := and(owner, _BITMASK_ADDRESS)
      // `owner | (block.timestamp << _BITPOS_START_TIMESTAMP) | flags`.
      result := or(owner, or(shl(_BITPOS_START_TIMESTAMP, timestamp()), flags))
    }
  }

  /**
   * @dev Returns the `nextInitialized` flag set if `quantity` equals 1.
   */
  function _nextInitializedFlag(uint256 quantity)
    private
    pure
    returns (uint256 result)
  {
    // For branchless setting of the `nextInitialized` flag.
    assembly {
      // `(quantity == 1) << _BITPOS_NEXT_INITIALIZED`.
      result := shl(_BITPOS_NEXT_INITIALIZED, eq(quantity, 1))
    }
  }

  // =============================================================
  //                      APPROVAL OPERATIONS
  // =============================================================

  /**
   * @dev Gives permission to `to` to transfer `tokenId` token to another account.
   * The approval is cleared when the token is transferred.
   *
   * Only a single account can be approved at a time, so approving the
   * zero address clears previous approvals.
   *
   * Requirements:
   *
   * - The caller must own the token or be an approved operator.
   * - `tokenId` must exist.
   *
   * Emits an {Approval} event.
   */
  function approve(address to, uint256 tokenId) public virtual override {
    address owner = ownerOf(tokenId);

    if (_msgSenderERC721A() != owner)
      if (!isApprovedForAll(owner, _msgSenderERC721A())) {
        revert ApprovalCallerNotOwnerNorApproved();
      }

    _tokenApprovals[tokenId].value = to;
    emit Approval(owner, to, tokenId);
  }

  /**
   * @dev Returns the account approved for `tokenId` token.
   *
   * Requirements:
   *
   * - `tokenId` must exist.
   */
  function getApproved(uint256 tokenId)
    public
    view
    virtual
    override
    returns (address)
  {
    if (!_exists(tokenId)) revert ApprovalQueryForNonexistentToken();

    return _tokenApprovals[tokenId].value;
  }

  /**
   * @dev Approve or remove `operator` as an operator for the caller.
   * Operators can call {transferFrom} or {safeTransferFrom}
   * for any token owned by the caller.
   *
   * Requirements:
   *
   * - The `operator` cannot be the caller.
   *
   * Emits an {ApprovalForAll} event.
   */
  function setApprovalForAll(address operator, bool approved)
    public
    virtual
    override
  {
    if (operator == _msgSenderERC721A()) revert ApproveToCaller();

    _operatorApprovals[_msgSenderERC721A()][operator] = approved;
    emit ApprovalForAll(_msgSenderERC721A(), operator, approved);
  }

  /**
   * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
   *
   * See {setApprovalForAll}.
   */
  function isApprovedForAll(address owner, address operator)
    public
    view
    virtual
    override
    returns (bool)
  {
    return _operatorApprovals[owner][operator];
  }

  /**
   * @dev Returns whether `tokenId` exists.
   *
   * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
   *
   * Tokens start existing when they are minted. See {_mint}.
   */
  function _exists(uint256 tokenId) internal view virtual returns (bool) {
    return
      _startTokenId() <= tokenId &&
      tokenId < _currentIndex && // If within bounds,
      _packedOwnerships[tokenId] & _BITMASK_BURNED == 0; // and not burned.
  }

  /**
   * @dev Returns whether `msgSender` is equal to `approvedAddress` or `owner`.
   */
  function _isSenderApprovedOrOwner(
    address approvedAddress,
    address owner,
    address msgSender
  ) private pure returns (bool result) {
    assembly {
      // Mask `owner` to the lower 160 bits, in case the upper bits somehow aren't clean.
      owner := and(owner, _BITMASK_ADDRESS)
      // Mask `msgSender` to the lower 160 bits, in case the upper bits somehow aren't clean.
      msgSender := and(msgSender, _BITMASK_ADDRESS)
      // `msgSender == owner || msgSender == approvedAddress`.
      result := or(eq(msgSender, owner), eq(msgSender, approvedAddress))
    }
  }

  /**
   * @dev Returns the storage slot and value for the approved address of `tokenId`.
   */
  function _getApprovedSlotAndAddress(uint256 tokenId)
    private
    view
    returns (uint256 approvedAddressSlot, address approvedAddress)
  {
    TokenApprovalRef storage tokenApproval = _tokenApprovals[tokenId];
    // The following is equivalent to `approvedAddress = _tokenApprovals[tokenId]`.
    assembly {
      approvedAddressSlot := tokenApproval.slot
      approvedAddress := sload(approvedAddressSlot)
    }
  }

  // =============================================================
  //                      TRANSFER OPERATIONS
  // =============================================================

  /**
   * @dev Transfers `tokenId` from `from` to `to`.
   *
   * Requirements:
   *
   * - `from` cannot be the zero address.
   * - `to` cannot be the zero address.
   * - `tokenId` token must be owned by `from`.
   * - If the caller is not `from`, it must be approved to move this token
   * by either {approve} or {setApprovalForAll}.
   *
   * Emits a {Transfer} event.
   */
  function transferFrom(
    address from,
    address to,
    uint256 tokenId
  ) public virtual override {
    uint256 prevOwnershipPacked = _packedOwnershipOf(tokenId);

    if (address(uint160(prevOwnershipPacked)) != from)
      revert TransferFromIncorrectOwner();

    (
      uint256 approvedAddressSlot,
      address approvedAddress
    ) = _getApprovedSlotAndAddress(tokenId);

    // The nested ifs save around 20+ gas over a compound boolean condition.
    if (!_isSenderApprovedOrOwner(approvedAddress, from, _msgSenderERC721A()))
      if (!isApprovedForAll(from, _msgSenderERC721A()))
        revert TransferCallerNotOwnerNorApproved();

    if (to == address(0)) revert TransferToZeroAddress();

    _beforeTokenTransfers(from, to, tokenId, 1);

    // Clear approvals from the previous owner.
    assembly {
      if approvedAddress {
        // This is equivalent to `delete _tokenApprovals[tokenId]`.
        sstore(approvedAddressSlot, 0)
      }
    }

    // Underflow of the sender's balance is impossible because we check for
    // ownership above and the recipient's balance can't realistically overflow.
    // Counter overflow is incredibly unrealistic as `tokenId` would have to be 2**256.
    unchecked {
      // We can directly increment and decrement the balances.
      --_packedAddressData[from]; // Updates: `balance -= 1`.
      ++_packedAddressData[to]; // Updates: `balance += 1`.

      // Updates:
      // - `address` to the next owner.
      // - `startTimestamp` to the timestamp of transfering.
      // - `burned` to `false`.
      // - `nextInitialized` to `true`.
      _packedOwnerships[tokenId] = _packOwnershipData(
        to,
        _BITMASK_NEXT_INITIALIZED |
          _nextExtraData(from, to, prevOwnershipPacked)
      );

      // If the next slot may not have been initialized (i.e. `nextInitialized == false`) .
      if (prevOwnershipPacked & _BITMASK_NEXT_INITIALIZED == 0) {
        uint256 nextTokenId = tokenId + 1;
        // If the next slot's address is zero and not burned (i.e. packed value is zero).
        if (_packedOwnerships[nextTokenId] == 0) {
          // If the next slot is within bounds.
          if (nextTokenId != _currentIndex) {
            // Initialize the next slot to maintain correctness for `ownerOf(tokenId + 1)`.
            _packedOwnerships[nextTokenId] = prevOwnershipPacked;
          }
        }
      }
    }

    emit Transfer(from, to, tokenId);
    _afterTokenTransfers(from, to, tokenId, 1);
  }

  /**
   * @dev Equivalent to `safeTransferFrom(from, to, tokenId, '')`.
   */
  function safeTransferFrom(
    address from,
    address to,
    uint256 tokenId
  ) public virtual override {
    safeTransferFrom(from, to, tokenId, '');
  }

  /**
   * @dev Safely transfers `tokenId` token from `from` to `to`.
   *
   * Requirements:
   *
   * - `from` cannot be the zero address.
   * - `to` cannot be the zero address.
   * - `tokenId` token must exist and be owned by `from`.
   * - If the caller is not `from`, it must be approved to move this token
   * by either {approve} or {setApprovalForAll}.
   * - If `to` refers to a smart contract, it must implement
   * {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
   *
   * Emits a {Transfer} event.
   */
  function safeTransferFrom(
    address from,
    address to,
    uint256 tokenId,
    bytes memory _data
  ) public virtual override {
    transferFrom(from, to, tokenId);
    if (to.code.length != 0)
      if (!_checkContractOnERC721Received(from, to, tokenId, _data)) {
        revert TransferToNonERC721ReceiverImplementer();
      }
  }

  /**
   * @dev Hook that is called before a set of serially-ordered token IDs
   * are about to be transferred. This includes minting.
   * And also called before burning one token.
   *
   * `startTokenId` - the first token ID to be transferred.
   * `quantity` - the amount to be transferred.
   *
   * Calling conditions:
   *
   * - When `from` and `to` are both non-zero, `from`'s `tokenId` will be
   * transferred to `to`.
   * - When `from` is zero, `tokenId` will be minted for `to`.
   * - When `to` is zero, `tokenId` will be burned by `from`.
   * - `from` and `to` are never both zero.
   */
  function _beforeTokenTransfers(
    address from,
    address to,
    uint256 startTokenId,
    uint256 quantity
  ) internal virtual {}

  /**
   * @dev Hook that is called after a set of serially-ordered token IDs
   * have been transferred. This includes minting.
   * And also called after one token has been burned.
   *
   * `startTokenId` - the first token ID to be transferred.
   * `quantity` - the amount to be transferred.
   *
   * Calling conditions:
   *
   * - When `from` and `to` are both non-zero, `from`'s `tokenId` has been
   * transferred to `to`.
   * - When `from` is zero, `tokenId` has been minted for `to`.
   * - When `to` is zero, `tokenId` has been burned by `from`.
   * - `from` and `to` are never both zero.
   */
  function _afterTokenTransfers(
    address from,
    address to,
    uint256 startTokenId,
    uint256 quantity
  ) internal virtual {}

  /**
   * @dev Private function to invoke {IERC721Receiver-onERC721Received} on a target contract.
   *
   * `from` - Previous owner of the given token ID.
   * `to` - Target address that will receive the token.
   * `tokenId` - Token ID to be transferred.
   * `_data` - Optional data to send along with the call.
   *
   * Returns whether the call correctly returned the expected magic value.
   */
  function _checkContractOnERC721Received(
    address from,
    address to,
    uint256 tokenId,
    bytes memory _data
  ) private returns (bool) {
    try
      ERC721A__IERC721Receiver(to).onERC721Received(
        _msgSenderERC721A(),
        from,
        tokenId,
        _data
      )
    returns (bytes4 retval) {
      return retval == ERC721A__IERC721Receiver(to).onERC721Received.selector;
    } catch (bytes memory reason) {
      if (reason.length == 0) {
        revert TransferToNonERC721ReceiverImplementer();
      } else {
        assembly {
          revert(add(32, reason), mload(reason))
        }
      }
    }
  }

  // =============================================================
  //                        MINT OPERATIONS
  // =============================================================

  /**
   * @dev Mints `quantity` tokens and transfers them to `to`.
   *
   * Requirements:
   *
   * - `to` cannot be the zero address.
   * - `quantity` must be greater than 0.
   *
   * Emits a {Transfer} event for each mint.
   */
  function _mint(address to, uint256 quantity) internal virtual {
    uint256 startTokenId = _currentIndex;
    require(quantity > 0, 'ERC721a: Mint Zero Quantity!');

    _beforeTokenTransfers(address(0), to, startTokenId, quantity);

    // Overflows are incredibly unrealistic.
    // `balance` and `numberMinted` have a maximum limit of 2**64.
    // `tokenId` has a maximum limit of 2**256.
    unchecked {
      // Updates:
      // - `balance += quantity`.
      // - `numberMinted += quantity`.
      //
      // We can directly add to the `balance` and `numberMinted`.
      _packedAddressData[to] += quantity * ((1 << _BITPOS_NUMBER_MINTED) | 1);

      // Updates:
      // - `address` to the owner.
      // - `startTimestamp` to the timestamp of minting.
      // - `burned` to `false`.
      // - `nextInitialized` to `quantity == 1`.
      _packedOwnerships[startTokenId] = _packOwnershipData(
        to,
        _nextInitializedFlag(quantity) | _nextExtraData(address(0), to, 0)
      );

      uint256 toMasked;
      uint256 end = startTokenId + quantity;

      // Use assembly to loop and emit the `Transfer` event for gas savings.
      assembly {
        // Mask `to` to the lower 160 bits, in case the upper bits somehow aren't clean.
        toMasked := and(to, _BITMASK_ADDRESS)
        // Emit the `Transfer` event.
        log4(
          0, // Start of data (0, since no data).
          0, // End of data (0, since no data).
          _TRANSFER_EVENT_SIGNATURE, // Signature.
          0, // `address(0)`.
          toMasked, // `to`.
          startTokenId // `tokenId`.
        )

        for {
          let tokenId := add(startTokenId, 1)
        } iszero(eq(tokenId, end)) {
          tokenId := add(tokenId, 1)
        } {
          // Emit the `Transfer` event. Similar to above.
          log4(0, 0, _TRANSFER_EVENT_SIGNATURE, 0, toMasked, tokenId)
        }
      }
      if (toMasked == 0) revert MintToZeroAddress();

      _currentIndex = end;
    }
    _afterTokenTransfers(address(0), to, startTokenId, quantity);
  }

  /**
   * @dev Mints `quantity` tokens and transfers them to `to`.
   *
   * This function is intended for efficient minting only during contract creation.
   *
   * It emits only one {ConsecutiveTransfer} as defined in
   * [ERC2309](https://eips.ethereum.org/EIPS/eip-2309),
   * instead of a sequence of {Transfer} event(s).
   *
   * Calling this function outside of contract creation WILL make your contract
   * non-compliant with the ERC721 standard.
   * For full ERC721 compliance, substituting ERC721 {Transfer} event(s) with the ERC2309
   * {ConsecutiveTransfer} event is only permissible during contract creation.
   *
   * Requirements:
   *
   * - `to` cannot be the zero address.
   * - `quantity` must be greater than 0.
   *
   * Emits a {ConsecutiveTransfer} event.
   */
  function _mintERC2309(address to, uint256 quantity) internal virtual {
    uint256 startTokenId = _currentIndex;
    if (to == address(0)) revert MintToZeroAddress();
    if (quantity == 0) revert MintZeroQuantity();
    if (quantity > _MAX_MINT_ERC2309_QUANTITY_LIMIT)
      revert MintERC2309QuantityExceedsLimit();

    _beforeTokenTransfers(address(0), to, startTokenId, quantity);

    // Overflows are unrealistic due to the above check for `quantity` to be below the limit.
    unchecked {
      // Updates:
      // - `balance += quantity`.
      // - `numberMinted += quantity`.
      //
      // We can directly add to the `balance` and `numberMinted`.
      _packedAddressData[to] += quantity * ((1 << _BITPOS_NUMBER_MINTED) | 1);

      // Updates:
      // - `address` to the owner.
      // - `startTimestamp` to the timestamp of minting.
      // - `burned` to `false`.
      // - `nextInitialized` to `quantity == 1`.
      _packedOwnerships[startTokenId] = _packOwnershipData(
        to,
        _nextInitializedFlag(quantity) | _nextExtraData(address(0), to, 0)
      );

      emit ConsecutiveTransfer(
        startTokenId,
        startTokenId + quantity - 1,
        address(0),
        to
      );

      _currentIndex = startTokenId + quantity;
    }
    _afterTokenTransfers(address(0), to, startTokenId, quantity);
  }

  /**
   * @dev Safely mints `quantity` tokens and transfers them to `to`.
   *
   * Requirements:
   *
   * - If `to` refers to a smart contract, it must implement
   * {IERC721Receiver-onERC721Received}, which is called for each safe transfer.
   * - `quantity` must be greater than 0.
   *
   * See {_mint}.
   *
   * Emits a {Transfer} event for each mint.
   */
  function _safeMint(
    address to,
    uint256 quantity,
    bytes memory _data
  ) internal virtual {
    _mint(to, quantity);

    unchecked {
      if (to.code.length != 0) {
        uint256 end = _currentIndex;
        uint256 index = end - quantity;
        do {
          if (!_checkContractOnERC721Received(address(0), to, index++, _data)) {
            revert TransferToNonERC721ReceiverImplementer();
          }
        } while (index < end);
        // Reentrancy protection.
        if (_currentIndex != end) revert();
      }
    }
  }

  /**
   * @dev Equivalent to `_safeMint(to, quantity, '')`.
   */
  function _safeMint(address to, uint256 quantity) internal virtual {
    _safeMint(to, quantity, '');
  }

  // =============================================================
  //                        BURN OPERATIONS
  // =============================================================

  /**
   * @dev Equivalent to `_burn(tokenId, false)`.
   */
  function _burn(uint256 tokenId) internal virtual {
    _burn(tokenId, false);
  }

  /**
   * @dev Destroys `tokenId`.
   * The approval is cleared when the token is burned.
   *
   * Requirements:
   *
   * - `tokenId` must exist.
   *
   * Emits a {Transfer} event.
   */
  function _burn(uint256 tokenId, bool approvalCheck) internal virtual {
    uint256 prevOwnershipPacked = _packedOwnershipOf(tokenId);

    address from = address(uint160(prevOwnershipPacked));

    (
      uint256 approvedAddressSlot,
      address approvedAddress
    ) = _getApprovedSlotAndAddress(tokenId);

    if (approvalCheck) {
      // The nested ifs save around 20+ gas over a compound boolean condition.
      if (!_isSenderApprovedOrOwner(approvedAddress, from, _msgSenderERC721A()))
        if (!isApprovedForAll(from, _msgSenderERC721A()))
          revert TransferCallerNotOwnerNorApproved();
    }

    _beforeTokenTransfers(from, address(0), tokenId, 1);

    // Clear approvals from the previous owner.
    assembly {
      if approvedAddress {
        // This is equivalent to `delete _tokenApprovals[tokenId]`.
        sstore(approvedAddressSlot, 0)
      }
    }

    // Underflow of the sender's balance is impossible because we check for
    // ownership above and the recipient's balance can't realistically overflow.
    // Counter overflow is incredibly unrealistic as `tokenId` would have to be 2**256.
    unchecked {
      // Updates:
      // - `balance -= 1`.
      // - `numberBurned += 1`.
      //
      // We can directly decrement the balance, and increment the number burned.
      // This is equivalent to `packed -= 1; packed += 1 << _BITPOS_NUMBER_BURNED;`.
      _packedAddressData[from] += (1 << _BITPOS_NUMBER_BURNED) - 1;

      // Updates:
      // - `address` to the last owner.
      // - `startTimestamp` to the timestamp of burning.
      // - `burned` to `true`.
      // - `nextInitialized` to `true`.
      _packedOwnerships[tokenId] = _packOwnershipData(
        from,
        (_BITMASK_BURNED | _BITMASK_NEXT_INITIALIZED) |
          _nextExtraData(from, address(0), prevOwnershipPacked)
      );

      // If the next slot may not have been initialized (i.e. `nextInitialized == false`) .
      if (prevOwnershipPacked & _BITMASK_NEXT_INITIALIZED == 0) {
        uint256 nextTokenId = tokenId + 1;
        // If the next slot's address is zero and not burned (i.e. packed value is zero).
        if (_packedOwnerships[nextTokenId] == 0) {
          // If the next slot is within bounds.
          if (nextTokenId != _currentIndex) {
            // Initialize the next slot to maintain correctness for `ownerOf(tokenId + 1)`.
            _packedOwnerships[nextTokenId] = prevOwnershipPacked;
          }
        }
      }
    }

    emit Transfer(from, address(0), tokenId);
    _afterTokenTransfers(from, address(0), tokenId, 1);

    // Overflow not possible, as _burnCounter cannot be exceed _currentIndex times.
    unchecked {
      _burnCounter++;
    }
  }

  // =============================================================
  //                     EXTRA DATA OPERATIONS
  // =============================================================

  /**
   * @dev Directly sets the extra data for the ownership data `index`.
   */
  function _setExtraDataAt(uint256 index, uint24 extraData) internal virtual {
    uint256 packed = _packedOwnerships[index];
    if (packed == 0) revert OwnershipNotInitializedForExtraData();
    uint256 extraDataCasted;
    // Cast `extraData` with assembly to avoid redundant masking.
    assembly {
      extraDataCasted := extraData
    }
    packed =
      (packed & _BITMASK_EXTRA_DATA_COMPLEMENT) |
      (extraDataCasted << _BITPOS_EXTRA_DATA);
    _packedOwnerships[index] = packed;
  }

  /**
   * @dev Called during each token transfer to set the 24bit `extraData` field.
   * Intended to be overridden by the cosumer contract.
   *
   * `previousExtraData` - the value of `extraData` before transfer.
   *
   * Calling conditions:
   *
   * - When `from` and `to` are both non-zero, `from`'s `tokenId` will be
   * transferred to `to`.
   * - When `from` is zero, `tokenId` will be minted for `to`.
   * - When `to` is zero, `tokenId` will be burned by `from`.
   * - `from` and `to` are never both zero.
   */
  function _extraData(
    address from,
    address to,
    uint24 previousExtraData
  ) internal view virtual returns (uint24) {}

  /**
   * @dev Returns the next extra data for the packed ownership data.
   * The returned result is shifted into position.
   */
  function _nextExtraData(
    address from,
    address to,
    uint256 prevOwnershipPacked
  ) private view returns (uint256) {
    uint24 extraData = uint24(prevOwnershipPacked >> _BITPOS_EXTRA_DATA);
    return uint256(_extraData(from, to, extraData)) << _BITPOS_EXTRA_DATA;
  }

  // =============================================================
  //                       OTHER OPERATIONS
  // =============================================================

  /**
   * @dev Returns the message sender (defaults to `msg.sender`).
   *
   * If you are writing GSN compatible contracts, you need to override this function.
   */
  function _msgSenderERC721A() internal view virtual returns (address) {
    return msg.sender;
  }

  /**
   * @dev Converts a uint256 to its ASCII string decimal representation.
   */
  function _toString(uint256 value)
    internal
    pure
    virtual
    returns (string memory str)
  {
    assembly {
      // The maximum value of a uint256 contains 78 digits (1 byte per digit),
      // but we allocate 0x80 bytes to keep the free memory pointer 32-byte word aliged.
      // We will need 1 32-byte word to store the length,
      // and 3 32-byte words to store a maximum of 78 digits. Total: 0x20 + 3 * 0x20 = 0x80.
      str := add(mload(0x40), 0x80)
      // Update the free memory pointer to allocate.
      mstore(0x40, str)

      // Cache the end of the memory to calculate the length later.
      let end := str

      // We write the string from rightmost digit to leftmost digit.
      // The following is essentially a do-while loop that also handles the zero case.
      // prettier-ignore
      for { let temp := value } 1 {} {
                str := sub(str, 1)
                // Write the character to the pointer.
                // The ASCII index of the '0' character is 48.
                mstore8(str, add(48, mod(temp, 10)))
                // Keep dividing `temp` until zero.
                temp := div(temp, 10)
                // prettier-ignore
                if iszero(temp) { break }
            }

      let length := sub(end, str)
      // Move the pointer 32 bytes leftwards to make room for the length.
      str := sub(str, 0x20)
      // Store the length.
      mstore(str, length)
    }
  }
}

// File: IERC165.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: IERC2981.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (interfaces/IERC2981.sol)

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Interface for the NFT Royalty Standard.
 *
 * A standardized way to retrieve royalty payment information for non-fungible tokens (NFTs) to enable universal
 * support for royalty payments across all NFT marketplaces and ecosystem participants.
 *
 * _Available since v4.5._
 */
interface IERC2981 is IERC165 {
    /**
     * @dev Returns how much royalty is owed and to whom, based on a sale price that may be denominated in any unit of
     * exchange. The royalty amount is denominated and should be paid in that same unit of exchange.
     */
    function royaltyInfo(uint256 tokenId, uint256 salePrice)
        external
        view
        returns (address receiver, uint256 royaltyAmount);
}

// File: IERC721A.sol



// SPDX-License-Identifier: MIT
// ERC721A Contracts v4.2.0
// Creator: Chiru Labs

pragma solidity ^0.8.4;

/**
 * @dev Interface of ERC721A.
 */
interface IERC721A {
    /**
     * The caller must own the token or be an approved operator.
     */
    error ApprovalCallerNotOwnerNorApproved();

    /**
     * The token does not exist.
     */
    error ApprovalQueryForNonexistentToken();

    /**
     * The caller cannot approve to their own address.
     */
    error ApproveToCaller();

    /**
     * Cannot query the balance for the zero address.
     */
    error BalanceQueryForZeroAddress();

    /**
     * Cannot mint to the zero address.
     */
    error MintToZeroAddress();

    /**
     * The quantity of tokens minted must be more than zero.
     */
    error MintZeroQuantity();

    /**
     * The token does not exist.
     */
    error OwnerQueryForNonexistentToken();

    /**
     * The caller must own the token or be an approved operator.
     */
    error TransferCallerNotOwnerNorApproved();

    /**
     * The token must be owned by `from`.
     */
    error TransferFromIncorrectOwner();

    /**
     * Cannot safely transfer to a contract that does not implement the
     * ERC721Receiver interface.
     */
    error TransferToNonERC721ReceiverImplementer();

    /**
     * Cannot transfer to the zero address.
     */
    error TransferToZeroAddress();

    /**
     * The token does not exist.
     */
    error URIQueryForNonexistentToken();

    /**
     * The `quantity` minted with ERC2309 exceeds the safety limit.
     */
    error MintERC2309QuantityExceedsLimit();

    /**
     * The `extraData` cannot be set on an unintialized ownership slot.
     */
    error OwnershipNotInitializedForExtraData();

    // =============================================================
    //                            STRUCTS
    // =============================================================

    struct TokenOwnership {
        // The address of the owner.
        address addr;
        // Stores the start time of ownership with minimal overhead for tokenomics.
        uint64 startTimestamp;
        // Whether the token has been burned.
        bool burned;
        // Arbitrary data similar to `startTimestamp` that can be set via {_extraData}.
        uint24 extraData;
    }

    // =============================================================
    //                         TOKEN COUNTERS
    // =============================================================

    /**
     * @dev Returns the total number of tokens in existence.
     * Burned tokens will reduce the count.
     * To get the total number of tokens minted, please see {_totalMinted}.
     */
    function totalSupply() external view returns (uint256);

    // =============================================================
    //                            IERC165
    // =============================================================

    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * [EIP section](https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified)
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);

    // =============================================================
    //                            IERC721
    // =============================================================

    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables
     * (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in `owner`'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`,
     * checking first that contract recipients are aware of the ERC721 protocol
     * to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move
     * this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement
     * {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data
    ) external;

    /**
     * @dev Equivalent to `safeTransferFrom(from, to, tokenId, '')`.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Transfers `tokenId` from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom}
     * whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token
     * by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the
     * zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom}
     * for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}.
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);

    // =============================================================
    //                        IERC721Metadata
    // =============================================================

    /**
     * @dev Returns the token collection name.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the token collection symbol.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
     */
    function tokenURI(uint256 tokenId) external view returns (string memory);

    // =============================================================
    //                           IERC2309
    // =============================================================

    /**
     * @dev Emitted when tokens in `fromTokenId` to `toTokenId`
     * (inclusive) is transferred from `from` to `to`, as defined in the
     * [ERC2309](https://eips.ethereum.org/EIPS/eip-2309) standard.
     *
     * See {_mintERC2309} for more details.
     */
    event ConsecutiveTransfer(uint256 indexed fromTokenId, uint256 toTokenId, address indexed from, address indexed to);
}

// File: MerkleProof.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (utils/cryptography/MerkleProof.sol)

pragma solidity ^0.8.0;

/**
 * @dev These functions deal with verification of Merkle Tree proofs.
 *
 * The proofs can be generated using the JavaScript library
 * https://github.com/miguelmota/merkletreejs[merkletreejs].
 * Note: the hashing algorithm should be keccak256 and pair sorting should be enabled.
 *
 * See `test/utils/cryptography/MerkleProof.test.js` for some examples.
 *
 * WARNING: You should avoid using leaf values that are 64 bytes long prior to
 * hashing, or use a hash function other than keccak256 for hashing leaves.
 * This is because the concatenation of a sorted pair of internal nodes in
 * the merkle tree could be reinterpreted as a leaf value.
 */
library MerkleProof {
    /**
     * @dev Returns true if a `leaf` can be proved to be a part of a Merkle tree
     * defined by `root`. For this, a `proof` must be provided, containing
     * sibling hashes on the branch from the leaf to the root of the tree. Each
     * pair of leaves and each pair of pre-images are assumed to be sorted.
     */
    function verify(
        bytes32[] memory proof,
        bytes32 root,
        bytes32 leaf
    ) internal pure returns (bool) {
        return processProof(proof, leaf) == root;
    }

    /**
     * @dev Calldata version of {verify}
     *
     * _Available since v4.7._
     */
    function verifyCalldata(
        bytes32[] calldata proof,
        bytes32 root,
        bytes32 leaf
    ) internal pure returns (bool) {
        return processProofCalldata(proof, leaf) == root;
    }

    /**
     * @dev Returns the rebuilt hash obtained by traversing a Merkle tree up
     * from `leaf` using `proof`. A `proof` is valid if and only if the rebuilt
     * hash matches the root of the tree. When processing the proof, the pairs
     * of leafs & pre-images are assumed to be sorted.
     *
     * _Available since v4.4._
     */
    function processProof(bytes32[] memory proof, bytes32 leaf) internal pure returns (bytes32) {
        bytes32 computedHash = leaf;
        for (uint256 i = 0; i < proof.length; i++) {
            computedHash = _hashPair(computedHash, proof[i]);
        }
        return computedHash;
    }

    /**
     * @dev Calldata version of {processProof}
     *
     * _Available since v4.7._
     */
    function processProofCalldata(bytes32[] calldata proof, bytes32 leaf) internal pure returns (bytes32) {
        bytes32 computedHash = leaf;
        for (uint256 i = 0; i < proof.length; i++) {
            computedHash = _hashPair(computedHash, proof[i]);
        }
        return computedHash;
    }

    /**
     * @dev Returns true if the `leaves` can be proved to be a part of a Merkle tree defined by
     * `root`, according to `proof` and `proofFlags` as described in {processMultiProof}.
     *
     * _Available since v4.7._
     */
    function multiProofVerify(
        bytes32[] memory proof,
        bool[] memory proofFlags,
        bytes32 root,
        bytes32[] memory leaves
    ) internal pure returns (bool) {
        return processMultiProof(proof, proofFlags, leaves) == root;
    }

    /**
     * @dev Calldata version of {multiProofVerify}
     *
     * _Available since v4.7._
     */
    function multiProofVerifyCalldata(
        bytes32[] calldata proof,
        bool[] calldata proofFlags,
        bytes32 root,
        bytes32[] memory leaves
    ) internal pure returns (bool) {
        return processMultiProofCalldata(proof, proofFlags, leaves) == root;
    }

    /**
     * @dev Returns the root of a tree reconstructed from `leaves` and the sibling nodes in `proof`,
     * consuming from one or the other at each step according to the instructions given by
     * `proofFlags`.
     *
     * _Available since v4.7._
     */
    function processMultiProof(
        bytes32[] memory proof,
        bool[] memory proofFlags,
        bytes32[] memory leaves
    ) internal pure returns (bytes32 merkleRoot) {
        // This function rebuild the root hash by traversing the tree up from the leaves. The root is rebuilt by
        // consuming and producing values on a queue. The queue starts with the `leaves` array, then goes onto the
        // `hashes` array. At the end of the process, the last hash in the `hashes` array should contain the root of
        // the merkle tree.
        uint256 leavesLen = leaves.length;
        uint256 totalHashes = proofFlags.length;

        // Check proof validity.
        require(leavesLen + proof.length - 1 == totalHashes, "MerkleProof: invalid multiproof");

        // The xxxPos values are "pointers" to the next value to consume in each array. All accesses are done using
        // `xxx[xxxPos++]`, which return the current value and increment the pointer, thus mimicking a queue's "pop".
        bytes32[] memory hashes = new bytes32[](totalHashes);
        uint256 leafPos = 0;
        uint256 hashPos = 0;
        uint256 proofPos = 0;
        // At each step, we compute the next hash using two values:
        // - a value from the "main queue". If not all leaves have been consumed, we get the next leaf, otherwise we
        //   get the next hash.
        // - depending on the flag, either another value for the "main queue" (merging branches) or an element from the
        //   `proof` array.
        for (uint256 i = 0; i < totalHashes; i++) {
            bytes32 a = leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++];
            bytes32 b = proofFlags[i] ? leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++] : proof[proofPos++];
            hashes[i] = _hashPair(a, b);
        }

        if (totalHashes > 0) {
            return hashes[totalHashes - 1];
        } else if (leavesLen > 0) {
            return leaves[0];
        } else {
            return proof[0];
        }
    }

    /**
     * @dev Calldata version of {processMultiProof}
     *
     * _Available since v4.7._
     */
    function processMultiProofCalldata(
        bytes32[] calldata proof,
        bool[] calldata proofFlags,
        bytes32[] memory leaves
    ) internal pure returns (bytes32 merkleRoot) {
        // This function rebuild the root hash by traversing the tree up from the leaves. The root is rebuilt by
        // consuming and producing values on a queue. The queue starts with the `leaves` array, then goes onto the
        // `hashes` array. At the end of the process, the last hash in the `hashes` array should contain the root of
        // the merkle tree.
        uint256 leavesLen = leaves.length;
        uint256 totalHashes = proofFlags.length;

        // Check proof validity.
        require(leavesLen + proof.length - 1 == totalHashes, "MerkleProof: invalid multiproof");

        // The xxxPos values are "pointers" to the next value to consume in each array. All accesses are done using
        // `xxx[xxxPos++]`, which return the current value and increment the pointer, thus mimicking a queue's "pop".
        bytes32[] memory hashes = new bytes32[](totalHashes);
        uint256 leafPos = 0;
        uint256 hashPos = 0;
        uint256 proofPos = 0;
        // At each step, we compute the next hash using two values:
        // - a value from the "main queue". If not all leaves have been consumed, we get the next leaf, otherwise we
        //   get the next hash.
        // - depending on the flag, either another value for the "main queue" (merging branches) or an element from the
        //   `proof` array.
        for (uint256 i = 0; i < totalHashes; i++) {
            bytes32 a = leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++];
            bytes32 b = proofFlags[i] ? leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++] : proof[proofPos++];
            hashes[i] = _hashPair(a, b);
        }

        if (totalHashes > 0) {
            return hashes[totalHashes - 1];
        } else if (leavesLen > 0) {
            return leaves[0];
        } else {
            return proof[0];
        }
    }

    function _hashPair(bytes32 a, bytes32 b) private pure returns (bytes32) {
        return a < b ? _efficientHash(a, b) : _efficientHash(b, a);
    }

    function _efficientHash(bytes32 a, bytes32 b) private pure returns (bytes32 value) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, a)
            mstore(0x20, b)
            value := keccak256(0x00, 0x40)
        }
    }
}

// File: Ownable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import './Context.sol';

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
  address private _owner;

  event OwnershipTransferred(
    address indexed previousOwner,
    address indexed newOwner
  );

  /**
   * @dev Initializes the contract setting the deployer as the initial owner.
   */
  constructor() {
    _transferOwnership(_msgSender());
  }

  /**
   * @dev Throws if called by any account other than the owner.
   */
  modifier onlyOwner() {
    _checkOwner();
    _;
  }

  /**
   * @dev Returns the address of the current owner.
   */
  function owner() public view virtual returns (address) {
    return _owner;
  }

  /**
   * @dev Throws if the sender is not the owner.
   */
  function _checkOwner() internal view virtual {
    require(owner() == _msgSender(), 'Ownable: caller is not the owner');
  }

  /**
   * @dev Leaves the contract without owner. It will not be possible to call
   * `onlyOwner` functions anymore. Can only be called by the current owner.
   *
   * NOTE: Renouncing ownership will leave the contract without an owner,
   * thereby removing any functionality that is only available to the owner.
   */
  function renounceOwnership() public virtual onlyOwner {
    _transferOwnership(address(0));
  }

  /**
   * @dev Transfers ownership of the contract to a new account (`newOwner`).
   * Can only be called by the current owner.
   */
  function transferOwnership(address newOwner) public virtual onlyOwner {
    require(newOwner != address(0), 'Ownable: new owner is the zero address');
    _transferOwnership(newOwner);
  }

  /**
   * @dev Transfers ownership of the contract to a new account (`newOwner`).
   * Internal function without access restriction.
   */
  function _transferOwnership(address newOwner) internal virtual {
    address oldOwner = _owner;
    _owner = newOwner;
    emit OwnershipTransferred(oldOwner, newOwner);
  }
}

// File: Retrogression.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.9;

import './Ownable.sol';
import './Address.sol';
import './MerkleProof.sol';
import './Strings.sol';
import './SafeMath.sol';
import './ERC721A.sol';
import './ERC2981.sol';

error PublicSaleNotLive();
error WhiteListNotLive();
error OgListNotLive();
error ExceededLimit();
error NotEnoughTokensLeft();
error WrongEther();
error InvalidMerkle();
error OgListUsed();
error WhitelistUsed();
error MintZeroQuantity();

contract Retrogression is ERC721A, ERC2981, Ownable {
  using Address for address;
  using SafeMath for uint256;
  using MerkleProof for bytes32[];

  bytes32 public whiteListMerkleRoot; // root hash for verying whitelist address
  uint256 public whiteListMaxMint; // max mint each address can mint
  uint256 public totalMaxSupply; // total max supply
  uint256 public ogMaxSupply; // og max supply
  uint256 public whiteListMaxSupply; // white list max supply
  uint256 public mintRate; // 150USD worth of ETH
  uint256 public whitelistMintRate; // 150USD worth of ETH
  uint256 public totalOgSupply; // og minted supply
  uint256 public totalWhiteListSupply; // whitelist minted supply
  string public baseExtension = '.json';
  string public baseURI = ''; // ipfs://<LIVE_CID>/
  string public baseHiddenUri = ''; // unreveal url
  bool public isWhitelistSale; // a boolean to handle stages of whitelist sale
  bool public isPublicSale; // a boolean to handle stages of public sale
  bool public revealed; // a boolean to indicate revealing of token.
  address payable public feeCollecter;

  /**
   * @dev a mapping to check the max mint for each address.
   */
  mapping(address => uint256) public whiteListUsedAddresses;

  constructor() ERC721A('RETROGRESSION - Rise of the Dark Army', 'RTGN') {
    mintRate = 150000000000000000; // 0.15eth tbc
    whitelistMintRate = 150000000000000000; // 0.15eth tbc
    whiteListMaxMint = 2;
    totalMaxSupply = 5462; // OG/EI and Character NFT
    ogMaxSupply = 412;
    whiteListMaxSupply = 200;
    isWhitelistSale = false;
    isPublicSale = false;
    revealed = false;
    feeCollecter = payable(0x02A522D98EC2D2c3bBe91AcC29ee7fD32ab880ab);
    baseHiddenUri = 'ipfs://QmegkArmJMKAWXGFFKETuoCFJAfsE6hoJRM2khgkZCvf5y/';
    whiteListMerkleRoot = 0x1e833049290a0843af727836cc7627d8742335ddd0073243c21f9186c5b3ba9d;

    // @dev setting the royalty fee for retrogression address.
    _setDefaultRoyalty(0xb8623497431893Fc4820eC708003f27DE086FEF1, 250);
  }

  modifier isPublicLive() {
    if (!isPublicSale) revert PublicSaleNotLive();
    _;
  }

  modifier isWhiteListLive() {
    if (!isWhitelistSale) revert WhiteListNotLive();
    _;
  }

  modifier isEnoughTokensLeft(uint256 _quantity) {
    if (_quantity.add(totalSupply()) > totalMaxSupply)
      revert NotEnoughTokensLeft();
    _;
  }

  modifier isAddressVerified(bytes32[] calldata _proof, bytes32 _rootHash) {
    if (!MerkleProof.verify(_proof, _rootHash, leaf(msg.sender)))
      revert InvalidMerkle();
    _;
  }

  modifier isWithinOgMintLimit(uint256 _quantity) {
    if (_quantity > ogMaxSupply) revert ExceededLimit();
    _;
  }

  modifier isWithinWhiteListMintLimit(uint256 _quantity) {
    if (_quantity > whiteListMaxSupply) revert ExceededLimit();
    _;
  }

  modifier isCorrectPayment(uint256 _quantity, uint256 _mintRate) {
    if (_quantity <= 0) revert MintZeroQuantity();
    if (_mintRate.mul(_quantity) != msg.value) revert WrongEther();
    _;
  }

  modifier checkQuantity(uint256 _quantity) {
    if (_quantity <= 0) revert MintZeroQuantity();
    _;
  }

  event SendFee(address from, address to, uint256 amount);

  /**
   * @dev a function to send 10% to dev account.
   */
  function sendFee() internal {
    uint256 fee = msg.value.mul(10).div(100); // deduct 10% from minting and send to mintable account
    require(address(this).balance >= fee, 'Address: insufficient balance');
    feeCollecter.transfer(fee);
    emit SendFee(address(this), feeCollecter, fee);
  }

  /**
   * @dev overrides contract supportInterface
   */
  function supportsInterface(bytes4 _interfaceId)
    public
    view
    virtual
    override(ERC721A, ERC2981)
    returns (bool)
  {
    return
      ERC721A.supportsInterface(_interfaceId) ||
      ERC2981.supportsInterface(_interfaceId);
  }

  /**
   * @dev a function that uses ERC721A is an improved implementation of the
   * IERC721 standard that supports minting multiple tokens for close to the cost of one
   *
   * handle oglist mint
   */
  function ogMint(uint256 _quantity)
    external
    payable
    onlyOwner
    checkQuantity(_quantity)
    isWithinOgMintLimit(_quantity)
    isEnoughTokensLeft(_quantity)
  {
    totalOgSupply = totalOgSupply.add(_quantity);
    sendFee();
    _mint(msg.sender, _quantity);
  }

  /**
   * @dev a function that uses ERC721A is an improved implementation of the
   * IERC721 standard that supports minting multiple tokens for close to the cost of one
   *
   * handle whitelist mint
   */
  function whiteListMint(uint256 _quantity, bytes32[] calldata _proof)
    external
    payable
    isWhiteListLive
    isAddressVerified(_proof, whiteListMerkleRoot)
    isWithinWhiteListMintLimit(_quantity)
    isEnoughTokensLeft(_quantity)
    isCorrectPayment(_quantity, whitelistMintRate)
  {
    if (_quantity.add(whiteListUsedAddresses[msg.sender]) > whiteListMaxMint) {
      revert WhitelistUsed();
    }

    whiteListUsedAddresses[msg.sender] = _quantity.add(
      whiteListUsedAddresses[msg.sender]
    );
    totalWhiteListSupply = _quantity.add(totalWhiteListSupply);

    sendFee();
    _mint(msg.sender, _quantity);
  }

  /**
   * @dev a function that uses ERC721A is an improved implementation of the
   * IERC721 standard that supports minting multiple tokens for close to the cost of one
   */
  function mint(uint256 _quantity)
    external
    payable
    isPublicLive
    isEnoughTokensLeft(_quantity)
    isCorrectPayment(_quantity, mintRate)
  {
    sendFee();
    _mint(msg.sender, _quantity);
  }

  function tokenURI(uint256 _tokenId)
    public
    view
    override
    returns (string memory)
  {
    require(_exists(_tokenId), 'ERC721a: token nonexistent!');

    if (!revealed) {
      string memory currentHiddenBaseURI = _baseHiddenURI();

      return
        bytes(currentHiddenBaseURI).length > 0
          ? string(
            abi.encodePacked(
              currentHiddenBaseURI,
              Strings.toString(_tokenId),
              baseExtension
            )
          )
          : '';
    }

    // added reveal
    string memory currentBaseURI = _baseURI();
    return
      bytes(currentBaseURI).length > 0
        ? string(
          abi.encodePacked(
            currentBaseURI,
            Strings.toString(_tokenId),
            baseExtension
          )
        )
        : '';
  }

  function _baseURI() internal view override returns (string memory) {
    return baseURI;
  }

  function _baseHiddenURI() internal view returns (string memory) {
    return baseHiddenUri;
  }

  function leaf(address _account) internal pure returns (bytes32) {
    return keccak256(abi.encodePacked(_account));
  }

  function setWhiteListMerkleRoot(bytes32 _root) external onlyOwner {
    whiteListMerkleRoot = _root;
  }

  function toggleWhitelistSale() public onlyOwner {
    isWhitelistSale = !isWhitelistSale;
  }

  function togglePublicSale() public onlyOwner {
    isPublicSale = !isPublicSale;
  }

  function setBaseURI(string memory _newBaseURI) public onlyOwner {
    baseURI = _newBaseURI;
    revealed = !revealed;
  }

  function withdraw() external payable onlyOwner {
    payable(msg.sender).transfer(address(this).balance);
  }
}

// File: SafeMath.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (utils/math/SafeMath.sol)

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

// File: Strings.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
    uint8 private constant _ADDRESS_LENGTH = 20;

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

    /**
     * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
     */
    function toHexString(address addr) internal pure returns (string memory) {
        return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
    }
}