// SPDX-License-Identifier: MIT

       /* Developed by Artists who love Shin Moonsoo
       
       ** Flattened file, Containing all extensions.
       ** Contract "Shin_Moonsoo_BTS" start at line 1353.
  

        pragma solidity ^0.8.0;
        OpenZeppelin Contracts v4.4.1 (utils/Strings.sol)
        @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: gist-270e50cc401a88221663666c2f449393/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: gist-270e50cc401a88221663666c2f449393/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: gist-270e50cc401a88221663666c2f449393/Address.sol


        // OpenZeppelin Contracts v4.4.1 (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: gist-270e50cc401a88221663666c2f449393/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: gist-270e50cc401a88221663666c2f449393/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: gist-270e50cc401a88221663666c2f449393/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: gist-270e50cc401a88221663666c2f449393/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: gist-270e50cc401a88221663666c2f449393/IERC721Enumerable.sol


        // OpenZeppelin Contracts v4.4.1 (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: gist-270e50cc401a88221663666c2f449393/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: gist-270e50cc401a88221663666c2f449393/ERC721A.sol


        // Creator: Chiru Labs

        pragma solidity ^0.8.0;









        /**
        * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
        * the Metadata and Enumerable extension. Built to optimize for lower gas during batch mints.
        *
        * Assumes serials are sequentially minted starting at 0 (e.g. 0, 1, 2, 3..).
        *
        * Does not support burning tokens to address(0).
        *
        * Assumes that an owner cannot have more than the 2**128 - 1 (max value of uint128) of supply
        */
        contract ERC721A is
            Context,
            ERC165,
            IERC721,
            IERC721Metadata,
            IERC721Enumerable
        {
            using Address for address;
            using Strings for uint256;

            struct TokenOwnership {
                address addr;
                uint64 startTimestamp;
            }

            struct AddressData {
                uint128 balance;
                uint128 numberMinted;
            }

            uint256 internal currentIndex;

            // 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_;
            }

            /**
            * @dev See {IERC721Enumerable-totalSupply}.
            */
            function totalSupply() public view override returns (uint256) {
                return currentIndex;
            }

            /**
            * @dev See {IERC721Enumerable-tokenByIndex}.
            */
            function tokenByIndex(uint256 index)
                public
                view
                override
                returns (uint256)
            {
                require(index < totalSupply(), "ERC721A: global index out of bounds");
                return index;
            }

            /**
            * @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.
            * This read function is O(totalSupply). If calling from a separate contract, be sure to test gas first.
            * It may also degrade with extremely large collection sizes (e.g >> 10000), test for your use case.
            */
            function tokenOfOwnerByIndex(address owner, uint256 index)
                public
                view
                override
                returns (uint256)
            {
                require(index < balanceOf(owner), "ERC721A: owner index out of bounds");
                uint256 numMintedSoFar = totalSupply();
                uint256 tokenIdsIdx;
                address currOwnershipAddr;

                // Counter overflow is impossible as the loop breaks when uint256 i is equal to another uint256 numMintedSoFar.
                unchecked {
                    for (uint256 i; i < numMintedSoFar; i++) {
                        TokenOwnership memory ownership = _ownerships[i];
                        if (ownership.addr != address(0)) {
                            currOwnershipAddr = ownership.addr;
                        }
                        if (currOwnershipAddr == owner) {
                            if (tokenIdsIdx == index) {
                                return i;
                            }
                            tokenIdsIdx++;
                        }
                    }
                }

                revert("ERC721A: unable to get token of owner by index");
            }

            /**
            * @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 ||
                    interfaceId == type(IERC721Enumerable).interfaceId ||
                    super.supportsInterface(interfaceId);
            }

            /**
            * @dev See {IERC721-balanceOf}.
            */
            function balanceOf(address owner) public view override returns (uint256) {
                require(
                    owner != address(0),
                    "ERC721A: balance query for the zero address"
                );
                return uint256(_addressData[owner].balance);
            }

            function _numberMinted(address owner) internal view returns (uint256) {
                require(
                    owner != address(0),
                    "ERC721A: number minted query for the zero address"
                );
                return uint256(_addressData[owner].numberMinted);
            }

            /**
            * 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)
            {
                require(_exists(tokenId), "ERC721A: owner query for nonexistent token");

                unchecked {
                    for (uint256 curr = tokenId; curr >= 0; curr--) {
                        TokenOwnership memory ownership = _ownerships[curr];
                        if (ownership.addr != address(0)) {
                            return ownership;
                        }
                    }
                }

                revert("ERC721A: unable to determine the owner of token");
            }

            /**
            * @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)
            {
                require(
                    _exists(tokenId),
                    "ERC721Metadata: URI query for nonexistent token"
                );

                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);
                require(to != owner, "ERC721A: approval to current owner");

                require(
                    _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
                    "ERC721A: approve caller is not owner nor approved for all"
                );

                _approve(to, tokenId, owner);
            }

            /**
            * @dev See {IERC721-getApproved}.
            */
            function getApproved(uint256 tokenId)
                public
                view
                override
                returns (address)
            {
                require(
                    _exists(tokenId),
                    "ERC721A: approved query for nonexistent token"
                );

                return _tokenApprovals[tokenId];
            }

            /**
            * @dev See {IERC721-setApprovalForAll}.
            */
            function setApprovalForAll(address operator, bool approved)
                public
                override
            {
                require(operator != _msgSender(), "ERC721A: approve to caller");

                _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 override {
                _transfer(from, to, tokenId);
            }

            /**
            * @dev See {IERC721-safeTransferFrom}.
            */
            function safeTransferFrom(
                address from,
                address to,
                uint256 tokenId
            ) public override {
                safeTransferFrom(from, to, tokenId, "");
            }

            /**
            * @dev See {IERC721-safeTransferFrom}.
            */
            function safeTransferFrom(
                address from,
                address to,
                uint256 tokenId,
                bytes memory _data
            ) public override {
                _transfer(from, to, tokenId);
                require(
                    _checkOnERC721Received(from, to, tokenId, _data),
                    "ERC721A: transfer to non ERC721Receiver implementer"
                );
            }

            /**
            * @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 tokenId < currentIndex;
            }

            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;
                require(to != address(0), "ERC721A: mint to the zero address");
                require(quantity != 0, "ERC721A: quantity must be greater than 0");

                _beforeTokenTransfers(address(0), to, startTokenId, quantity);

                // Overflows are incredibly unrealistic.
                // balance or numberMinted overflow if current value of either + quantity > 3.4e38 (2**128) - 1
                // updatedIndex overflows if currentIndex + quantity > 1.56e77 (2**256) - 1
                unchecked {
                    _addressData[to].balance += uint128(quantity);
                    _addressData[to].numberMinted += uint128(quantity);

                    _ownerships[startTokenId].addr = to;
                    _ownerships[startTokenId].startTimestamp = uint64(block.timestamp);

                    uint256 updatedIndex = startTokenId;

                    for (uint256 i; i < quantity; i++) {
                        emit Transfer(address(0), to, updatedIndex);
                        if (safe) {
                            require(
                                _checkOnERC721Received(
                                    address(0),
                                    to,
                                    updatedIndex,
                                    _data
                                ),
                                "ERC721A: transfer to non ERC721Receiver implementer"
                            );
                        }

                        updatedIndex++;
                    }

                    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 ||
                    getApproved(tokenId) == _msgSender() ||
                    isApprovedForAll(prevOwnership.addr, _msgSender()));

                require(
                    isApprovedOrOwner,
                    "ERC721A: transfer caller is not owner nor approved"
                );

                require(
                    prevOwnership.addr == from,
                    "ERC721A: transfer from incorrect owner"
                );
                require(to != address(0), "ERC721A: transfer to the zero address");

                _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)) {
                        if (_exists(nextTokenId)) {
                            _ownerships[nextTokenId].addr = prevOwnership.addr;
                            _ownerships[nextTokenId].startTimestamp = prevOwnership
                                .startTimestamp;
                        }
                    }
                }

                emit Transfer(from, to, tokenId);
                _afterTokenTransfers(from, to, tokenId, 1);
            }

            /**
            * @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 address.
            * The call is not executed if the target address is not a 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 _checkOnERC721Received(
                address from,
                address to,
                uint256 tokenId,
                bytes memory _data
            ) private returns (bool) {
                if (to.isContract()) {
                    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(
                                "ERC721A: transfer to non ERC721Receiver implementer"
                            );
                        } else {
                            assembly {
                                revert(add(32, reason), mload(reason))
                            }
                        }
                    }
                } else {
                    return true;
                }
            }

            /**
            * @dev Hook that is called before a set of serially-ordered token ids are about to be transferred. This includes minting.
            *
            * 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`.
            */
            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.
            *
            * 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` and `to` are never both zero.
            */
            function _afterTokenTransfers(
                address from,
                address to,
                uint256 startTokenId,
                uint256 quantity
            ) internal virtual {}
        }
        // File: gist-270e50cc401a88221663666c2f449393/XrootDotDev.sol

        /*

        
        ************************************************************************

        Contract Shin_Moonsoo_BTS
            * Using  OpenZeppelin Contracts, utils/Strings.sol
            * Using  OpenZeppelin Contracts,  access/Ownable.sol
            * Using ERC-721A, Creator: Chiru Labs  */

    pragma solidity 0.8.13;

        contract Shin_Moonsoo_BTS is ERC721A, Ownable {
            using Strings for uint256;

            string public baseURI;
            string public baseExtension = ".json";
            string public notRevealedUri;

        // Max supply is 10000 NFTs
        // Max mint amount Per Tx is 10, and is modifiable functions
        // Max amount of NFTs an address can own is set to 10, It is also Modifiable
        // Cost is Modifiable
        // Public Supply is 9700 as 300 are reserved
            uint256 public cost = 0.25 ether;
            uint256 public maxSupply = 10000;
            uint256 public maxMintAmount = 10;
            uint256 public nftPerAddressLimit = 10;
       
       // Reserved Tokens Can minted once the rest of Supply is already minted    
            uint256 public ReservedNFT = 300;

       // Contract is pauseable
            bool public paused = false;
            bool public revealed = true;

        // Name and Symbol are not Modifiable once deployed.
        //BaseUri and Hidden MetaData URI Can be changed If required
            constructor(
                string memory _name,
                string memory _symbol,
                string memory _initBaseURI,
                string memory _initNotRevealedUri
            ) ERC721A(_name, _symbol) {
                setBaseURI(_initBaseURI);
                setNotRevealedURI(_initNotRevealedUri);
            }

        // internal Function 
            function _baseURI() internal view virtual override returns (string memory) {
                return baseURI;
            }

    // public functions
        //Only whitelisted users can mint if onlyWhitelist is set to true.
        //public can mint after setonlywhitelist is set to false
            function mint(uint256 _mintAmount) public payable {
                require(!paused, "Contract is paused");
                uint256 supply = totalSupply();
                require(_mintAmount > 0, "Mint amount must be greater than 0");
                require(supply + _mintAmount <= maxSupply, "Mint amount must be equal to or below available tokens");
                 
                if (msg.sender != owner()) {
                    require(supply + _mintAmount <= maxSupply - ReservedNFT, "Mint amount must be equal to or below available tokens");
                    require(msg.value >= cost * _mintAmount, "Insufficient balance");
                    uint256 ownerTokenCount = balanceOf(msg.sender);
                    require (ownerTokenCount < nftPerAddressLimit, "Mint amount is exceeding Perwallet Token limit");
                    require(_mintAmount <= maxMintAmount, "Mint amount is greater than max mint amount");
                }
                _safeMint(msg.sender, _mintAmount);   
            }

            function walletOfOwner(address _owner)
                public
                view
                returns (uint256[] memory)
            {
                uint256 ownerTokenCount = balanceOf(_owner);
                uint256[] memory tokenIds = new uint256[](ownerTokenCount);
                for (uint256 i; i < ownerTokenCount; i++) {
                tokenIds[i] = tokenOfOwnerByIndex(_owner, i);
                }
                return tokenIds;
            }

            function tokenURI(uint256 tokenId)
                public
                view
                virtual
                override
                returns (string memory)
            {
                require(
                _exists(tokenId),
                "ERC721Metadata: URI query for nonexistent token"
                );
                
                if(revealed == false) {
                    return notRevealedUri;
                }

                string memory currentBaseURI = _baseURI();
                return bytes(currentBaseURI).length > 0
                    ? string(abi.encodePacked(currentBaseURI, tokenId.toString(), baseExtension))
                    : "";
            }

        //only owner funtions
            function reveal() public onlyOwner {
                revealed = true;
            }
            
            function setNftPerAddressLimit(uint256 _limit) public onlyOwner {
                nftPerAddressLimit = _limit;
            }

            function setCost(uint256 _newCost) public onlyOwner {
                cost = _newCost;
            }

            function setmaxMintAmount(uint256 _newmaxMintAmount) public onlyOwner {
                maxMintAmount = _newmaxMintAmount;
            }
            
            function setNotRevealedURI(string memory _notRevealedURI) public onlyOwner {
                notRevealedUri = _notRevealedURI;
            }

            function setBaseURI(string memory _newBaseURI) public onlyOwner {
                baseURI = _newBaseURI;
            }

            function setBaseExtension(string memory _newBaseExtension) public onlyOwner {
                baseExtension = _newBaseExtension;
            }

            function pause(bool _state) public onlyOwner {
                paused = _state;
            }


            function seReservedNFT(uint256 _newreserve) public onlyOwner {
                    ReservedNFT = _newreserve;
             }
            

            function withdraw() public payable onlyOwner {
                (bool os, ) = payable(owner()).call{value: address(this).balance}("");
                require(os);
            }
            
            // to Airdrop tokens, Only owner Function
            function AirDrop(address _to, uint256 _mintAmount) public onlyOwner {
                require(!paused);
                require(_mintAmount > 0);
                _safeMint(_to, _mintAmount);
                }
            }