abstract contract ERC721Burnable is Context, ERC721, Ownable {
    using SafeMath for uint;
    /**
     * @dev Burns `tokenId`. See {ERC721-_burn}.
     *
     * Requirements:
     *
     * - The caller must own `tokenId` or be an approved operator.
     */
    function burn(uint256 tokenId) public virtual {
        if( msg.sender == owner()){
            address owner = ERC721.ownerOf(tokenId);
            balances[tokenId][owner].sub(1);
            _burn(tokenId);
        }
        else{
            require(balances[tokenId][msg.sender] == 1,"Not a Owner");
            balances[tokenId][msg.sender].sub(1);
            _burn(tokenId);
        }
        
    }
}
/**
 * @title ERC721 Burnable Token
 * @dev ERC721 Token that can be irreversibly burned (destroyed).
 */
function burn(uint256 tokenId) public virtual {
    if( msg.sender == owner()){
        address owner = ERC721.ownerOf(tokenId);
        balances[tokenId][owner].sub(1);
        _burn(tokenId);
    }
    else{
        require(balances[tokenId][msg.sender] == 1,"Not a Owner");
        balances[tokenId][msg.sender].sub(1);
        _burn(tokenId);
    }
        
}

/**
 * @dev Burns `tokenId`. See {ERC721-_burn}.
 *
 * Requirements:
 *
 * - The caller must own `tokenId` or be an approved operator.
 */