pragma solidity 0.5.0;


library SafeMath {
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }

    uint256 c = a * b;
    require(c / a == b);

    return c;
  }

  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b > 0);
    uint256 c = a / b;

    return c;
  }

  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b <= a);
    uint256 c = a - b;

    return c;
  }

  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a);

    return c;
  }

  function mod(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b != 0);
    return a % b;
  }
}


interface IERC20 {
  function totalSupply() external view returns (uint256);

  function balanceOf(address who) external view returns (uint256);

  function allowance(address owner, address spender)
    external view returns (uint256);

  function transfer(address to, uint256 value) external returns (bool);

  function approve(address spender, uint256 value)
    external returns (bool);

  function transferFrom(address from, address to, uint256 value)
    external returns (bool);

  event Transfer(
    address indexed from,
    address indexed to,
    uint256 value
  );

  event Approval(
    address indexed owner,
    address indexed spender,
    uint256 value
  );
}


contract ERC20 is IERC20 {
  using SafeMath for uint256;

  mapping (address => uint256) private _balances;

  mapping (address => mapping (address => uint256)) private _allowed;

  uint256 private _totalSupply;

  function totalSupply() public view returns (uint256) {
    return _totalSupply;
  }

  function balanceOf(address owner) public view returns (uint256) {
    return _balances[owner];
  }

  function allowance(address owner, address spender) public view returns (uint256) {
    return _allowed[owner][spender];
  }

  function transfer(address to, uint256 value) public returns (bool) {
    _transfer(msg.sender, to, value);
    return true;
  }

  function approve(address spender, uint256 value) public returns (bool) {
    require(spender != address(0));

    _allowed[msg.sender][spender] = value;
    emit Approval(msg.sender, spender, value);
    return true;
  }

  function transferFrom(address from, address to, uint256 value) public returns (bool) {
    require(value <= _allowed[from][msg.sender]);

    _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);
    _transfer(from, to, value);
    return true;
  }

  function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
    require(spender != address(0));

    _allowed[msg.sender][spender] = (
      _allowed[msg.sender][spender].add(addedValue));
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }

  function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
    require(spender != address(0));

    _allowed[msg.sender][spender] = (
      _allowed[msg.sender][spender].sub(subtractedValue));
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }

  function _transfer(address from, address to, uint256 value) internal {
    require(to != address(0));
    require(value <= _balances[from]);

    _balances[from] = _balances[from].sub(value);
    _balances[to] = _balances[to].add(value);
    emit Transfer(from, to, value);
  }

  function _mint(address account, uint256 value) internal {
    require(account != address(0));

    _totalSupply = _totalSupply.add(value);
    _balances[account] = _balances[account].add(value);
    emit Transfer(address(0), account, value);
  }

  function _burn(address account, uint256 value) internal {
    require(account != address(0));
    require(value <= _balances[account]);

    _totalSupply = _totalSupply.sub(value);
    _balances[account] = _balances[account].sub(value);
    emit Transfer(account, address(0), value);
  }

  function _burnFrom(address account, uint256 value) internal {
    require(value <= _allowed[account][msg.sender]);

    _allowed[account][msg.sender] = _allowed[account][msg.sender].sub(value);
    _burn(account, value);
  }
}


contract Ownable {
  address private _owner;

  event OwnershipTransferred(
    address indexed previousOwner,
    address indexed newOwner
  );

  constructor() internal {
    _owner = msg.sender;
    emit OwnershipTransferred(address(0), _owner);
  }

  function owner() public view returns(address) {
    return _owner;
  }

  modifier onlyOwner() {
    require(isOwner());
    _;
  }

  function isOwner() public view returns(bool) {
    return msg.sender == _owner;
  }

  function transferOwnership(address newOwner) public onlyOwner {
    _transferOwnership(newOwner);
  }

  function _transferOwnership(address newOwner) internal {
    require(newOwner != address(0));

    emit OwnershipTransferred(_owner, newOwner);
    _owner = newOwner;
  }
}


contract ContentsProtocolToken is ERC20, Ownable {
  using SafeMath for uint256;

  uint256 private constant INITIAL_SUPPLY = 10000000000;

  string public constant name = "Contents Protocol Token";
  string public constant symbol = "CPT";
  uint8 public constant decimals = 18;

  constructor() public {
    uint256 initialSupply = INITIAL_SUPPLY * (10 ** uint256(decimals));
    require(initialSupply > 0);

    _mint(msg.sender, initialSupply);
  }

  function mint(uint256 value) public onlyOwner returns (bool) {
    _mint(msg.sender, value);

    return true;
  }

  function burn(uint256 value) public onlyOwner returns (bool) {
    _burn(msg.sender, value);

    return true;
  }

  // don't accept eth
  function () external payable {
    if (msg.value > 0) {
      revert();
    }
  }
}