// SPDX-License-Identifier: MIT
    pragma solidity ^0.8.0;
    
    //Written by Blockchainguy.net
    //Email: info@blockchainguy.net
    //tg: @sherazmanzoor
    
    /**
     * @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;
        }
    }
    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);
        }
    }
    pragma solidity ^0.8.0;
    
    /**
     * @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
         * ====
         */
        function isContract(address account) internal view returns (bool) {
            // This method relies on extcodesize, which returns 0 for contracts in
            // construction, since the code is only stored at the end of the
            // constructor execution.
    
            uint256 size;
            assembly {
                size := extcodesize(account)
            }
            return size > 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);
                }
            }
        }
    }
    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);
    }
    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);
    }
    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() {
            _setOwner(_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 {
            _setOwner(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");
            _setOwner(newOwner);
        }
    
        function _setOwner(address newOwner) private {
            address oldOwner = _owner;
            _owner = newOwner;
            emit OwnershipTransferred(oldOwner, newOwner);
        }
    }
    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;
        }
    }
    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;
    }
    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);
    }
    pragma solidity ^0.8.0;
    
    
    /**
     * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
     * the Metadata extension, but not including the Enumerable extension, which is available separately as
     * {ERC721Enumerable}.
     */
    contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
        using Address for address;
        using Strings for uint256;
    
        // Token name
        string private _name;
    
        // Token symbol
        string private _symbol;
    
        // Mapping from token ID to owner address
        mapping(uint256 => address) private _owners;
    
        // Mapping owner address to token count
        mapping(address => uint256) private _balances;
    
        // 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;
    
        /**
         * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
         */
        constructor(string memory name_, string memory symbol_) {
            _name = name_;
            _symbol = symbol_;
        }
    
        /**
         * @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 virtual override returns (uint256) {
            require(owner != address(0), "ERC721: balance query for the zero address");
            return _balances[owner];
        }
    
        /**
         * @dev See {IERC721-ownerOf}.
         */
        function ownerOf(uint256 tokenId) public view virtual override returns (address) {
            address owner = _owners[tokenId];
            require(owner != address(0), "ERC721: owner query for nonexistent token");
            return owner;
        }
    
        /**
         * @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 virtual override {
            address owner = ERC721.ownerOf(tokenId);
            require(to != owner, "ERC721: approval to current owner");
    
            require(
                _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
                "ERC721: approve caller is not owner nor approved for all"
            );
    
            _approve(to, tokenId);
        }
    
        /**
         * @dev See {IERC721-getApproved}.
         */
        function getApproved(uint256 tokenId) public view virtual override returns (address) {
            require(_exists(tokenId), "ERC721: approved query for nonexistent token");
    
            return _tokenApprovals[tokenId];
        }
    
        /**
         * @dev See {IERC721-setApprovalForAll}.
         */
        function setApprovalForAll(address operator, bool approved) public virtual override {
            require(operator != _msgSender(), "ERC721: 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 virtual override {
            //solhint-disable-next-line max-line-length
            require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
    
            _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 {
            require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
            _safeTransfer(from, to, tokenId, _data);
        }
    
        /**
         * @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.
         *
         * `_data` is additional data, it has no specified format and it is sent in call to `to`.
         *
         * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
         * implement alternative mechanisms to perform token transfer, such as signature-based.
         *
         * Requirements:
         *
         * - `from` cannot be the zero address.
         * - `to` cannot be the zero address.
         * - `tokenId` token must exist and be owned by `from`.
         * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
         *
         * Emits a {Transfer} event.
         */
        function _safeTransfer(
            address from,
            address to,
            uint256 tokenId,
            bytes memory _data
        ) internal virtual {
            _transfer(from, to, tokenId);
            require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: 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`),
         * and stop existing when they are burned (`_burn`).
         */
        function _exists(uint256 tokenId) internal view virtual returns (bool) {
            return _owners[tokenId] != address(0);
        }
    
        /**
         * @dev Returns whether `spender` is allowed to manage `tokenId`.
         *
         * Requirements:
         *
         * - `tokenId` must exist.
         */
        function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
            require(_exists(tokenId), "ERC721: operator query for nonexistent token");
            address owner = ERC721.ownerOf(tokenId);
            return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
        }
    
        /**
         * @dev Safely mints `tokenId` and transfers it to `to`.
         *
         * Requirements:
         *
         * - `tokenId` must not exist.
         * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
         *
         * Emits a {Transfer} event.
         */
        function _safeMint(address to, uint256 tokenId) internal virtual {
            _safeMint(to, tokenId, "");
        }
    
        /**
         * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
         * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
         */
        function _safeMint(
            address to,
            uint256 tokenId,
            bytes memory _data
        ) internal virtual {
            _mint(to, tokenId);
            require(
                _checkOnERC721Received(address(0), to, tokenId, _data),
                "ERC721: transfer to non ERC721Receiver implementer"
            );
        }
    
        /**
         * @dev Mints `tokenId` and transfers it to `to`.
         *
         * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
         *
         * Requirements:
         *
         * - `tokenId` must not exist.
         * - `to` cannot be the zero address.
         *
         * Emits a {Transfer} event.
         */
        function _mint(address to, uint256 tokenId) internal virtual {
            require(to != address(0), "ERC721: mint to the zero address");
            require(!_exists(tokenId), "ERC721: token already minted");
    
            _beforeTokenTransfer(address(0), to, tokenId);
    
            _balances[to] += 1;
            _owners[tokenId] = to;
    
            emit Transfer(address(0), to, tokenId);
        }
    
        /**
         * @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 {
            address owner = ERC721.ownerOf(tokenId);
    
            _beforeTokenTransfer(owner, address(0), tokenId);
    
            // Clear approvals
            _approve(address(0), tokenId);
    
            _balances[owner] -= 1;
            delete _owners[tokenId];
    
            emit Transfer(owner, address(0), tokenId);
        }
    
        /**
         * @dev Transfers `tokenId` from `from` to `to`.
         *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
         *
         * 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
        ) internal virtual {
            require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer of token that is not own");
            require(to != address(0), "ERC721: transfer to the zero address");
    
            _beforeTokenTransfer(from, to, tokenId);
    
            // Clear approvals from the previous owner
            _approve(address(0), tokenId);
    
            _balances[from] -= 1;
            _balances[to] += 1;
            _owners[tokenId] = to;
    
            emit Transfer(from, to, tokenId);
        }
    
        /**
         * @dev Approve `to` to operate on `tokenId`
         *
         * Emits a {Approval} event.
         */
        function _approve(address to, uint256 tokenId) internal virtual {
            _tokenApprovals[tokenId] = to;
            emit Approval(ERC721.ownerOf(tokenId), 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.onERC721Received.selector;
                } catch (bytes memory reason) {
                    if (reason.length == 0) {
                        revert("ERC721: transfer to non ERC721Receiver implementer");
                    } else {
                        assembly {
                            revert(add(32, reason), mload(reason))
                        }
                    }
                }
            } else {
                return true;
            }
        }
    
        /**
         * @dev Hook that is called before any token transfer. This includes minting
         * and burning.
         *
         * 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, ``from``'s `tokenId` will be burned.
         * - `from` and `to` are never both zero.
         *
         * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
         */
        function _beforeTokenTransfer(
            address from,
            address to,
            uint256 tokenId
        ) internal virtual {}
    }pragma solidity ^0.8.0;
    
    
    contract FutureBillionairesClubOriginal is Ownable, ERC721 {
        uint constant tokenPrice = 0.08 ether;
        uint public maxSupply = 3333;
        
        uint public totalSupply = 0;
        
        uint public sale_startTime = 1637258400;
        uint public presale_startTime = 1637172000;
        uint public reveal_time = 1637344800;
        bool public pause_sale = false;
        string public reveal_url = "https://gateway.pinata.cloud/ipfs/QmeVqW4nF6iXUAuUFocAKWUFLQhTXoPDfhUYBMWeTDqiT9/";
        string public baseURI = "https://apibillionare.vercel.app/api/nft/";
        mapping(address => bool) private presaleList;
        constructor() ERC721("Future Billionaires Club Original", "FBCO"){}
    
       function buy(uint _count) public payable{
            require(_count > 0, "mint at least one token");
            require(_count <= 20, "Max 20 Allowed.");
            require(totalSupply + _count <= maxSupply, "Not enough tokens left");
            require(msg.value == tokenPrice * _count, "incorrect ether amount");
            require(block.timestamp >= sale_startTime,"Sale not Started Yet.");
            require(pause_sale == false, "Sale is Paused.");
            
            for(uint i = 0; i < _count; i++)
                _safeMint(msg.sender, totalSupply + 1 + i);
                
                totalSupply += _count;
        }
       function buy_Presale(uint _count) public payable{
            require(_count > 0, "mint at least one token");
            require(_count <= 5, "Max 5 Allowed.");
            require(totalSupply + _count <= maxSupply, "Not enough tokens left");
            require(msg.value == tokenPrice * _count, "incorrect ether amount");
            require(block.timestamp >= presale_startTime,"Pre Sale not Started Yet.");
            require(block.timestamp < sale_startTime,"Pre Sale Ended.");
            require(pause_sale == false, "Sale is Paused.");
            require(checkPresale(), "You are not whitelisted.");
            
            for(uint i = 0; i < _count; i++)
                _safeMint(msg.sender, totalSupply + 1 + i);
                
                totalSupply += _count;
        }
        function sendGifts(address[] memory _wallets) public onlyOwner{
            require(totalSupply + _wallets.length <= maxSupply, "not enough tokens left");
            for(uint i = 0; i < _wallets.length; i++)
                _safeMint(_wallets[i], totalSupply + 1 + i);
            totalSupply += _wallets.length;
        }
    
        function addPresaleList(address[] memory _wallets) public onlyOwner{
            for(uint i; i < _wallets.length; i++)
                presaleList[_wallets[i]] = true;
        }
        
        function checkPresale() public view returns(bool){
            return presaleList[msg.sender];
        }
        
        function setBaseUri(string memory _uri) external onlyOwner {
            baseURI = _uri;
        }
        function setPauseSale(bool temp) external onlyOwner {
            pause_sale = temp;
        }
        function setRevealTime(uint temp) external onlyOwner {
            reveal_time = temp;
        }
        
        function _baseURI() internal view virtual override returns (string memory) {
            return baseURI;
        }
        function set_start_time(uint256 time) external onlyOwner{
            sale_startTime = time;
        }
        function set_presale_time(uint256 time) external onlyOwner{
            presale_startTime = time;
        }
        function set_max_supply(uint256 count) external onlyOwner{
            maxSupply = count;
        }
        function set_reveal_url(string memory url) external onlyOwner{
            reveal_url = url;
        }
        
        function tokenURI(uint tokenId) public view virtual override returns (string memory) {
            require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");
            if(block.timestamp < reveal_time ){
                return reveal_url;
            }
            
            return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId)) : "";
        }
        function isPresalestarted() external view returns (bool){
            if(block.timestamp >= presale_startTime && block.timestamp < sale_startTime){
                return true;
            }
            return false;
        }
        function withdraw() external onlyOwner {
            payable(owner()).transfer(address(this).balance);
        }
    }