// File: @openzeppelin/contracts/utils/Strings.sol


// OpenZeppelin Contracts v4.4.1 (utils/Strings.sol)

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**
     * @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);
    }
}

// File: @openzeppelin/contracts/utils/Context.sol


// 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: @openzeppelin/contracts/access/Ownable.sol


// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)

pragma solidity ^0.8.0;


/**
 * @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 Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        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: @openzeppelin/contracts/utils/Address.sol


// OpenZeppelin Contracts (last updated v4.5.0) (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 functionCall(target, data, "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");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(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) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(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) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason 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 {
            // 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

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol


// OpenZeppelin Contracts v4.4.1 (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol


// 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: @openzeppelin/contracts/utils/introspection/ERC165.sol


// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)

pragma solidity ^0.8.0;


/**
 * @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: @openzeppelin/contracts/token/ERC721/IERC721.sol


// OpenZeppelin Contracts v4.4.1 (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;


/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @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
    ) external;

    /**
     * @dev Transfers `tokenId` token 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 Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @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 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);

    /**
     * @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 calldata data
    ) external;
}

// File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Enumerable.sol


// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC721/extensions/IERC721Enumerable.sol)

pragma solidity ^0.8.0;


/**
 * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Enumerable is IERC721 {
    /**
     * @dev Returns the total amount of tokens stored by the contract.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns a token ID owned by `owner` at a given `index` of its token list.
     * Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256);

    /**
     * @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
     * Use along with {totalSupply} to enumerate all tokens.
     */
    function tokenByIndex(uint256 index) external view returns (uint256);
}

// File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol


// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/IERC721Metadata.sol)

pragma solidity ^0.8.0;


/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {
    /**
     * @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);
}

// File: contracts/ERC721A.sol



// Creator: Chiru Labs



pragma solidity ^0.8.4;











error ApprovalCallerNotOwnerNorApproved();

error ApprovalQueryForNonexistentToken();

error ApproveToCaller();

error ApprovalToCurrentOwner();

error BalanceQueryForZeroAddress();

error MintedQueryForZeroAddress();

error BurnedQueryForZeroAddress();

error AuxQueryForZeroAddress();

error MintToZeroAddress();

error MintZeroQuantity();

error OwnerIndexOutOfBounds();

error OwnerQueryForNonexistentToken();

error TokenIndexOutOfBounds();

error TransferCallerNotOwnerNorApproved();

error TransferFromIncorrectOwner();

error TransferToNonERC721ReceiverImplementer();

error TransferToZeroAddress();

error URIQueryForNonexistentToken();



/**

 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including

 * the Metadata extension. Built to optimize for lower gas during batch mints.

 *

 * Assumes serials are sequentially minted starting at _startTokenId() (defaults to 0, e.g. 0, 1, 2, 3..).

 *

 * Assumes that an owner cannot have more than 2**64 - 1 (max value of uint64) of supply.

 *

 * Assumes that the maximum token id cannot exceed 2**256 - 1 (max value of uint256).

 */

contract ERC721A is Context, ERC165, IERC721, IERC721Metadata {

    using Address for address;

    using Strings for uint256;



    // Compiler will pack this into a single 256bit word.

    struct TokenOwnership {

        // The address of the owner.

        address addr;

        // Keeps track of the start time of ownership with minimal overhead for tokenomics.

        uint64 startTimestamp;

        // Whether the token has been burned.

        bool burned;

    }



    // Compiler will pack this into a single 256bit word.

    struct AddressData {

        // Realistically, 2**64-1 is more than enough.

        uint64 balance;

        // Keeps track of mint count with minimal overhead for tokenomics.

        uint64 numberMinted;

        // Keeps track of burn count with minimal overhead for tokenomics.

        uint64 numberBurned;

        // For miscellaneous variable(s) pertaining to the address

        // (e.g. number of whitelist mint slots used).

        // If there are multiple variables, please pack them into a uint64.

        uint64 aux;

    }



    // The tokenId of the next token to be minted.

    uint256 internal _currentIndex;



    // The number of tokens burned.

    uint256 internal _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 ownershipOf implementation for details.

    mapping(uint256 => TokenOwnership) internal _ownerships;



    // Mapping owner address to address data

    mapping(address => AddressData) private _addressData;



    // Mapping from token ID to approved address

    mapping(uint256 => address) private _tokenApprovals;



    // Mapping from owner to operator approvals

    mapping(address => mapping(address => bool)) private _operatorApprovals;



    constructor(string memory name_, string memory symbol_) {

        _name = name_;

        _symbol = symbol_;

        _currentIndex = _startTokenId();

    }



    /**

     * To change the starting tokenId, please override this function.

     */

    function _startTokenId() internal view virtual returns (uint256) {

        return 0;

    }



    /**

     * @dev See {IERC721Enumerable-totalSupply}.

     * @dev Burned tokens are calculated here, use _totalMinted() if you want to count just minted tokens.

     */

    function totalSupply() public view returns (uint256) {

        // Counter underflow is impossible as _burnCounter cannot be incremented

        // more than _currentIndex - _startTokenId() times

        unchecked {

            return _currentIndex - _burnCounter - _startTokenId();

        }

    }



    /**

     * Returns the total amount of tokens minted in the contract.

     */

    function _totalMinted() internal view returns (uint256) {

        // Counter underflow is impossible as _currentIndex does not decrement,

        // and it is initialized to _startTokenId()

        unchecked {

            return _currentIndex - _startTokenId();

        }

    }



    /**

     * @dev See {IERC165-supportsInterface}.

     */

    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {

        return

            interfaceId == type(IERC721).interfaceId ||

            interfaceId == type(IERC721Metadata).interfaceId ||

            super.supportsInterface(interfaceId);

    }



    /**

     * @dev See {IERC721-balanceOf}.

     */

    function balanceOf(address owner) public view override returns (uint256) {

        if (owner == address(0)) revert BalanceQueryForZeroAddress();

        return uint256(_addressData[owner].balance);

    }



    /**

     * Returns the number of tokens minted by `owner`.

     */

    function _numberMinted(address owner) internal view returns (uint256) {

        if (owner == address(0)) revert MintedQueryForZeroAddress();

        return uint256(_addressData[owner].numberMinted);

    }



    /**

     * Returns the number of tokens burned by or on behalf of `owner`.

     */

    function _numberBurned(address owner) internal view returns (uint256) {

        if (owner == address(0)) revert BurnedQueryForZeroAddress();

        return uint256(_addressData[owner].numberBurned);

    }



    /**

     * Returns the auxillary data for `owner`. (e.g. number of whitelist mint slots used).

     */

    function _getAux(address owner) internal view returns (uint64) {

        if (owner == address(0)) revert AuxQueryForZeroAddress();

        return _addressData[owner].aux;

    }



    /**

     * Sets the auxillary 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 {

        if (owner == address(0)) revert AuxQueryForZeroAddress();

        _addressData[owner].aux = aux;

    }



    /**

     * Gas spent here starts off proportional to the maximum mint batch size.

     * It gradually moves to O(1) as tokens get transferred around in the collection over time.

     */

    function ownershipOf(uint256 tokenId) internal view returns (TokenOwnership memory) {

        uint256 curr = tokenId;



        unchecked {

            if (_startTokenId() <= curr && curr < _currentIndex) {

                TokenOwnership memory ownership = _ownerships[curr];

                if (!ownership.burned) {

                    if (ownership.addr != address(0)) {

                        return ownership;

                    }

                    // Invariant:

                    // There will always be an ownership that has an address and is not burned

                    // before an ownership that does not have an address and is not burned.

                    // Hence, curr will not underflow.

                    while (true) {

                        curr--;

                        ownership = _ownerships[curr];

                        if (ownership.addr != address(0)) {

                            return ownership;

                        }

                    }

                }

            }

        }

        revert OwnerQueryForNonexistentToken();

    }



    /**

     * @dev See {IERC721-ownerOf}.

     */

    function ownerOf(uint256 tokenId) public view override returns (address) {

        return ownershipOf(tokenId).addr;

    }



    /**

     * @dev See {IERC721Metadata-name}.

     */

    function name() public view virtual override returns (string memory) {

        return _name;

    }



    /**

     * @dev See {IERC721Metadata-symbol}.

     */

    function symbol() public view virtual override returns (string memory) {

        return _symbol;

    }



    /**

     * @dev See {IERC721Metadata-tokenURI}.

     */

    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, tokenId.toString())) : '';

    }



    /**

     * @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, can be overriden in child contracts.

     */

    function _baseURI() internal view virtual returns (string memory) {

        return '';

    }



    /**

     * @dev See {IERC721-approve}.

     */

    function approve(address to, uint256 tokenId) public override {

        address owner = ERC721A.ownerOf(tokenId);

        if (to == owner) revert ApprovalToCurrentOwner();



        if (_msgSender() != owner && !isApprovedForAll(owner, _msgSender())) {

            revert ApprovalCallerNotOwnerNorApproved();

        }



        _approve(to, tokenId, owner);

    }



    /**

     * @dev See {IERC721-getApproved}.

     */

    function getApproved(uint256 tokenId) public view override returns (address) {

        if (!_exists(tokenId)) revert ApprovalQueryForNonexistentToken();



        return _tokenApprovals[tokenId];

    }



    /**

     * @dev See {IERC721-setApprovalForAll}.

     */

    function setApprovalForAll(address operator, bool approved) public override {

        if (operator == _msgSender()) revert ApproveToCaller();



        _operatorApprovals[_msgSender()][operator] = approved;

        emit ApprovalForAll(_msgSender(), operator, approved);

    }



    /**

     * @dev See {IERC721-isApprovedForAll}.

     */

    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {

        return _operatorApprovals[owner][operator];

    }



    /**

     * @dev See {IERC721-transferFrom}.

     */

    function transferFrom(

        address from,

        address to,

        uint256 tokenId

    ) public virtual override {

        _transfer(from, to, tokenId);

    }



    /**

     * @dev See {IERC721-safeTransferFrom}.

     */

    function safeTransferFrom(

        address from,

        address to,

        uint256 tokenId

    ) public virtual override {

        safeTransferFrom(from, to, tokenId, '');

    }



    /**

     * @dev See {IERC721-safeTransferFrom}.

     */

    function safeTransferFrom(

        address from,

        address to,

        uint256 tokenId,

        bytes memory _data

    ) public virtual override {

        _transfer(from, to, tokenId);

        if (to.isContract() && !_checkContractOnERC721Received(from, to, tokenId, _data)) {

            revert TransferToNonERC721ReceiverImplementer();

        }

    }



    /**

     * @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 (`_mint`),

     */

    function _exists(uint256 tokenId) internal view returns (bool) {

        return _startTokenId() <= tokenId && tokenId < _currentIndex &&

            !_ownerships[tokenId].burned;

    }



    function _safeMint(address to, uint256 quantity) internal {

        _safeMint(to, 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.

     *

     * Emits a {Transfer} event.

     */

    function _safeMint(

        address to,

        uint256 quantity,

        bytes memory _data

    ) internal {

        _mint(to, quantity, _data, true);

    }



    /**

     * @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.

     */

    function _mint(

        address to,

        uint256 quantity,

        bytes memory _data,

        bool safe

    ) internal {

        uint256 startTokenId = _currentIndex;

        if (to == address(0)) revert MintToZeroAddress();

        if (quantity == 0) revert MintZeroQuantity();



        _beforeTokenTransfers(address(0), to, startTokenId, quantity);



        // Overflows are incredibly unrealistic.

        // balance or numberMinted overflow if current value of either + quantity > 1.8e19 (2**64) - 1

        // updatedIndex overflows if _currentIndex + quantity > 1.2e77 (2**256) - 1

        unchecked {

            _addressData[to].balance += uint64(quantity);

            _addressData[to].numberMinted += uint64(quantity);



            _ownerships[startTokenId].addr = to;

            _ownerships[startTokenId].startTimestamp = uint64(block.timestamp);



            uint256 updatedIndex = startTokenId;

            uint256 end = updatedIndex + quantity;



            if (safe && to.isContract()) {

                do {

                    emit Transfer(address(0), to, updatedIndex);

                    if (!_checkContractOnERC721Received(address(0), to, updatedIndex++, _data)) {

                        revert TransferToNonERC721ReceiverImplementer();

                    }

                } while (updatedIndex != end);

                // Reentrancy protection

                if (_currentIndex != startTokenId) revert();

            } else {

                do {

                    emit Transfer(address(0), to, updatedIndex++);

                } while (updatedIndex != end);

            }

            _currentIndex = updatedIndex;

        }

        _afterTokenTransfers(address(0), to, startTokenId, quantity);

    }



    /**

     * @dev Transfers `tokenId` from `from` to `to`.

     *

     * Requirements:

     *

     * - `to` cannot be the zero address.

     * - `tokenId` token must be owned by `from`.

     *

     * Emits a {Transfer} event.

     */

    function _transfer(

        address from,

        address to,

        uint256 tokenId

    ) private {

        TokenOwnership memory prevOwnership = ownershipOf(tokenId);



        bool isApprovedOrOwner = (_msgSender() == prevOwnership.addr ||

            isApprovedForAll(prevOwnership.addr, _msgSender()) ||

            getApproved(tokenId) == _msgSender());



        if (!isApprovedOrOwner) revert TransferCallerNotOwnerNorApproved();

        if (prevOwnership.addr != from) revert TransferFromIncorrectOwner();

        if (to == address(0)) revert TransferToZeroAddress();



        _beforeTokenTransfers(from, to, tokenId, 1);



        // Clear approvals from the previous owner

        _approve(address(0), tokenId, prevOwnership.addr);



        // 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 {

            _addressData[from].balance -= 1;

            _addressData[to].balance += 1;



            _ownerships[tokenId].addr = to;

            _ownerships[tokenId].startTimestamp = uint64(block.timestamp);



            // If the ownership slot of tokenId+1 is not explicitly set, that means the transfer initiator owns it.

            // Set the slot of tokenId+1 explicitly in storage to maintain correctness for ownerOf(tokenId+1) calls.

            uint256 nextTokenId = tokenId + 1;

            if (_ownerships[nextTokenId].addr == address(0)) {

                // This will suffice for checking _exists(nextTokenId),

                // as a burned slot cannot contain the zero address.

                if (nextTokenId < _currentIndex) {

                    _ownerships[nextTokenId].addr = prevOwnership.addr;

                    _ownerships[nextTokenId].startTimestamp = prevOwnership.startTimestamp;

                }

            }

        }



        emit Transfer(from, to, tokenId);

        _afterTokenTransfers(from, to, tokenId, 1);

    }



    /**

     * @dev Destroys `tokenId`.

     * The approval is cleared when the token is burned.

     *

     * Requirements:

     *

     * - `tokenId` must exist.

     *

     * Emits a {Transfer} event.

     */

    function _burn(uint256 tokenId) internal virtual {

        TokenOwnership memory prevOwnership = ownershipOf(tokenId);



        _beforeTokenTransfers(prevOwnership.addr, address(0), tokenId, 1);



        // Clear approvals from the previous owner

        _approve(address(0), tokenId, prevOwnership.addr);



        // 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 {

            _addressData[prevOwnership.addr].balance -= 1;

            _addressData[prevOwnership.addr].numberBurned += 1;



            // Keep track of who burned the token, and the timestamp of burning.

            _ownerships[tokenId].addr = prevOwnership.addr;

            _ownerships[tokenId].startTimestamp = uint64(block.timestamp);

            _ownerships[tokenId].burned = true;



            // If the ownership slot of tokenId+1 is not explicitly set, that means the burn initiator owns it.

            // Set the slot of tokenId+1 explicitly in storage to maintain correctness for ownerOf(tokenId+1) calls.

            uint256 nextTokenId = tokenId + 1;

            if (_ownerships[nextTokenId].addr == address(0)) {

                // This will suffice for checking _exists(nextTokenId),

                // as a burned slot cannot contain the zero address.

                if (nextTokenId < _currentIndex) {

                    _ownerships[nextTokenId].addr = prevOwnership.addr;

                    _ownerships[nextTokenId].startTimestamp = prevOwnership.startTimestamp;

                }

            }

        }



        emit Transfer(prevOwnership.addr, address(0), tokenId);

        _afterTokenTransfers(prevOwnership.addr, address(0), tokenId, 1);



        // Overflow not possible, as _burnCounter cannot be exceed _currentIndex times.

        unchecked {

            _burnCounter++;

        }

    }



    /**

     * @dev Approve `to` to operate on `tokenId`

     *

     * Emits a {Approval} event.

     */

    function _approve(

        address to,

        uint256 tokenId,

        address owner

    ) private {

        _tokenApprovals[tokenId] = to;

        emit Approval(owner, to, tokenId);

    }



    /**

     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target contract.

     *

     * @param from address representing the previous owner of the given token ID

     * @param to target address that will receive the tokens

     * @param tokenId uint256 ID of the token to be transferred

     * @param _data bytes optional data to send along with the call

     * @return bool whether the call correctly returned the expected magic value

     */

    function _checkContractOnERC721Received(

        address from,

        address to,

        uint256 tokenId,

        bytes memory _data

    ) private returns (bool) {

        try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {

            return retval == IERC721Receiver(to).onERC721Received.selector;

        } catch (bytes memory reason) {

            if (reason.length == 0) {

                revert TransferToNonERC721ReceiverImplementer();

            } else {

                assembly {

                    revert(add(32, reason), mload(reason))

                }

            }

        }

    }



    /**

     * @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 {}

}


// File: contracts/Ducks.sol



pragma solidity ^0.8.4;






contract Ducks is ERC721A, Ownable {

    string uriBase = "ipfs://QmdmFdAAJN2SNzDJzFwKSpY6Bamg1JpyskWpjiuzHaws4o/";

    string public baseExtension = ".json";

    uint256 public maxSupply = 5000;

    uint256 public cost = 0 ether;

    uint256 public maxMint = 3;

    uint256 public freePerUser = 3;

    bool public isSale = false;

    mapping(address => uint256) public addressesMintedBalance;



    constructor() ERC721A("Dishonored Disloyal Ducks", "DDD") { }



    function mint (uint256 quantity) external payable {

        uint256 supply = totalSupply();



        require(quantity > 0, "Invalid mint amount.");

        require(supply + quantity <= maxSupply, "Not enough tokens left.");



       if (msg.sender != owner()) {

            require(isSale, "Contract is paused.");

            uint256 senderMintedCount = addressesMintedBalance[msg.sender];

            require(quantity <= maxMint && senderMintedCount + quantity <= maxMint, "Max. NFT per address exceeded.");



            if(senderMintedCount + quantity > 3) {

                if(senderMintedCount >= 3) {

                    require(msg.value >= quantity*cost, "Invalid ETH amount sent");

                }

                else {

                    require(msg.value >= (quantity - freePerUser) * cost, "Invalid ETH amount sent");

                }

            }



            addressesMintedBalance[msg.sender] += quantity;

       }



       _safeMint(msg.sender, quantity);

    }



    function _baseURI() internal view override returns (string memory) {

        return uriBase;

    }



    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {

        require(_exists(tokenId), "Token already exists");

        return bytes(uriBase).length != 0 ? string(abi.encodePacked(uriBase, Strings.toString(tokenId), baseExtension)) : '';

    }



    function _startTokenId() internal view virtual override returns (uint256) {

        return 1;

    }



    function setMaxMintAmount(uint256 _newAmount) public onlyOwner {

        maxMint = _newAmount;

    }



    function setCost(uint256 _newCost) public onlyOwner {

        cost = _newCost;

    }



    function setBaseURI(string memory _newURI) public onlyOwner {

        uriBase = _newURI;

    }



    function setBaseExtension(string memory _newBaseExtension) public onlyOwner

    {

        baseExtension = _newBaseExtension;

    }



    function setIsSale(bool _state) public onlyOwner {

        isSale = _state;

    }



    function withdraw() external payable onlyOwner {

        payable(owner()).transfer(address(this).balance);

    }

}