ERC20 token

pragma solidity ^0.4.18;


contract Token {

    uint256 constant private MAX_UINT256 = 2**256 - 1;
    mapping(address => uint) public balances;
    mapping(address => mapping(address => uint)) public allowed;

    uint8 public decimals = 18; // Don't set this to anything other than 18, please
    string public name = "Dapper Network Token";
    string public symbol = "DPR";
    uint public totalSupply = 0; // actual current supply
    
    uint maximumSupply = 100000000 ether; // maximum supply
    uint cost = 100;
    
    address public creator;
    
    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
    
    function Token() public
    {
        balances[msg.sender] = totalSupply;
        creator = msg.sender;
    }

    // Don't let people randomly send ETH to contract
    function() public payable {
        revert();
    }
    
    function buy() public payable {        
        // Each ETH is worth 100 tokens
        uint amount = msg.value * cost;
        
        balances[msg.sender] += amount;
        totalSupply += amount;
        
        require(totalSupply < maximumSupply);
    }

    function transfer(address _to, uint256 _value) public returns (bool success) {
        require(balances[msg.sender] >= _value);
        balances[msg.sender] -= _value;
        balances[_to] += _value;
        Transfer(msg.sender, _to, _value);
        return true;
    }

    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        uint256 allowance = allowed[_from][msg.sender];
        require(balances[_from] >= _value && allowance >= _value);
        balances[_to] += _value;
        balances[_from] -= _value;
        if (allowance < MAX_UINT256) {
            allowed[_from][msg.sender] -= _value;
        }
        Transfer(_from, _to, _value);
        return true;
    }

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

    function approve(address _spender, uint256 _value) public returns (bool success) {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }

    function allowance(address _owner, address _spender) public view returns (uint256 remaining) {
        return allowed[_owner][_spender];
    }
  
    function withdraw(address to) {
      require(msg.sender == creator);
      to.send(this.balance);
    }
}