pragma solidity ^0.4.18;

contract SafeMath {

    function safeAdd(uint256 x, uint256 y) internal returns(uint256) {
        uint256 z = x + y;
        assert((z >= x) && (z >= y));
        return z;
    }

    function safeSubtract(uint256 x, uint256 y) internal returns(uint256) {
        assert(x >= y);
        uint256 z = x - y;
        return z;
    }

    function safeMult(uint256 x, uint256 y) internal returns(uint256) {
        uint256 z = x * y;
        assert((x == 0)||(z/x == y));
        return z;
    }
}

contract Token {
    uint256 public totalSupply;

    function balanceOf(address _owner) constant returns (uint256 balance);
    function transfer(address _to, uint256 _value) returns (bool success);
    function transferFrom(address _from, address _to, uint256 _value) returns (bool success);
    function approve(address _spender, uint256 _value) returns (bool success);
    function allowance(address _owner, address _spender) constant returns (uint256 remaining);

    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}

/*  ERC 20 token */
contract StandardToken is Token, SafeMath {

    mapping (address => uint256) balances;
    mapping (address => mapping (address => uint256)) allowed;

    modifier onlyPayloadSize(uint numwords) {
        assert(msg.data.length == numwords * 32 + 4);
        _;
    }

    function transfer(address _to, uint256 _value)
    returns (bool success)
    {
        if (balances[msg.sender] >= _value && _value > 0 && balances[_to] + _value > balances[_to]) {
            balances[msg.sender] = safeSubtract(balances[msg.sender], _value);
            balances[_to] = safeAdd(balances[_to], _value);
            Transfer(msg.sender, _to, _value);
            return true;
        } else {
            return false;
        }
    }

    function transferFrom(address _from, address _to, uint256 _value)
    returns (bool success)
    {
        if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && _value > 0 && balances[_to] + _value > balances[_to]) {
            balances[_to] = safeAdd(balances[_to], _value);
            balances[_from] = safeSubtract(balances[_from], _value);
            allowed[_from][msg.sender] = safeSubtract(allowed[_from][msg.sender], _value);
            Transfer(_from, _to, _value);
            return true;
        } else {
            return false;
        }
    }

    function balanceOf(address _owner) constant returns (uint256 balance) {
        return balances[_owner];
    }

    function approve(address _spender, uint256 _value)
    onlyPayloadSize(2)
    returns (bool success)
    {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }

    function allowance(address _owner, address _spender)
    constant
    onlyPayloadSize(2)
    returns (uint256 remaining)
    {
        return allowed[_owner][_spender];
    }
}
/**
 * @title NitroCoins
 * @dev ERC20 Token, where all tokens are pre-assigned to the creator.
 * Note they can later distribute these tokens as they wish using `transfer` and other
 * `StandardToken` functions.
 */
contract NitroCoins is StandardToken {

  string public name = "Nitro Coins";
  string public symbol = "NRC";
  uint256 public decimals = 18;
  uint256 public INITIAL_SUPPLY = 25000000 * 1 ether;

  /**
   * @dev Contructor that gives msg.sender all of existing tokens.
   */
  function NitroCoins() {
    totalSupply = INITIAL_SUPPLY;
    balances[msg.sender] = INITIAL_SUPPLY;
  }

}