pragma solidity ^0.4.23;

library SafeMath {
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }
    uint256 c = a * b;
    assert(c / a == b);
    return c;
  }

  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a / b;
    return c;
  }

  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
  }
}


contract BasicToken  {
  using SafeMath for uint256;

  string public name;
  string public symbol;
  uint8 public decimals = 18;

  uint256 _totalSupply;
  mapping(address => uint256) _balances;
  event Transfer(address indexed from, address indexed to, uint256 value);

  function totalSupply() public view returns (uint256) {
    return _totalSupply;
  }

  function balanceOf(address addr) public view returns (uint256 balance) {
    return _balances[addr];
  }

  function transfer(address to, uint256 value) public returns (bool) {
    require(to != address(0));
    require(value <= _balances[msg.sender]);

    _balances[msg.sender] = _balances[msg.sender].sub(value);
    _balances[to] = _balances[to].add(value);
    emit Transfer(msg.sender, to, value);
    return true;
  }


}

contract StandardToken is BasicToken {

  mapping (address => mapping (address => uint256)) _allowances;
  event Approval(address indexed owner, address indexed agent, uint256 value);

  function transferFrom(address from, address to, uint256 value) public returns (bool) {
    require(to != address(0));
    require(value <= _balances[from]);
    require(value <= _allowances[from][msg.sender]);

    _balances[from] = _balances[from].sub(value);
    _balances[to] = _balances[to].add(value);
    _allowances[from][msg.sender] = _allowances[from][msg.sender].sub(value);
    emit Transfer(from, to, value);
    return true;
  }

  function approve(address agent, uint256 value) public returns (bool) {
    _allowances[msg.sender][agent] = value;
    emit Approval(msg.sender, agent, value);
    return true;
  }

  function allowance(address owner, address agent) public view returns (uint256) {
    return _allowances[owner][agent];
  }

  function increaseApproval(address agent, uint value) public returns (bool) {
    _allowances[msg.sender][agent] = _allowances[msg.sender][agent].add(value);
    emit Approval(msg.sender, agent, _allowances[msg.sender][agent]);
    return true;
  }

  function decreaseApproval(address agent, uint value) public returns (bool) {
    uint allowanceValue = _allowances[msg.sender][agent];
    if (value > allowanceValue) {
      _allowances[msg.sender][agent] = 0;
    } else {
      _allowances[msg.sender][agent] = allowanceValue.sub(value);
    }
    emit Approval(msg.sender, agent, _allowances[msg.sender][agent]);
    return true;
  }
}


contract DSFToken is StandardToken {
  string public name = "DSF Token";
  string public symbol = "DSF";
  uint8 public decimals = 18;

  constructor() public {
    _totalSupply = 1 * (10 ** 10) * (10 ** uint256(decimals));

    _balances[msg.sender] = _totalSupply;
    emit Transfer(0x0, msg.sender, _totalSupply);
  }

}

{
  "compilationTarget": {
    "DSFToken.sol": "DSFToken"
  },
  "evmVersion": "byzantium",
  "libraries": {},
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}