pragma solidity ^0.4.24;
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 ERC20Basic {
  uint256 public totalSupply;
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
}
contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender) public view returns (uint256);
  function transferFrom(address from, address to, uint256 value) public returns (bool);
  function approve(address spender, uint256 value) public returns (bool);
  event Approval(address indexed owner, address indexed spender, uint256 value);
}
contract BasicToken is ERC20 {
  using SafeMath for uint256;
  mapping(address => uint256) balances;
  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);
    Transfer(msg.sender, _to, _value);
    return true;
  }
  function balanceOf(address _owner) public view returns (uint256 balance) {
    return balances[_owner];
  }
}
contract ERC20Standard is BasicToken {
  mapping (address => mapping (address => uint256)) internal allowed;
  function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));
    require(_value <= balances[_from]);
    require(_value <= allowed[_from][msg.sender]);
    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
    Transfer(_from, _to, _value);
    return true;
  }
  function approve(address _spender, uint256 _value) public returns (bool) {
    allowed[msg.sender][_spender] = _value;
    Approval(msg.sender, _spender, _value);
    return true;
  }
  function allowance(address _owner, address _spender) public view returns (uint256) {
    return allowed[_owner][_spender];
  }
  function increaseApproval(address _spender, uint _addedValue) public returns (bool) {
    allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
    Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }
  function decreaseApproval(address _spender, uint _subtractedValue) public returns (bool) {
    uint oldValue = allowed[msg.sender][_spender];
    if (_subtractedValue > oldValue) {
      allowed[msg.sender][_spender] = 0;
    } else {
      allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
    }
    Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }
}
contract ValkyrieNetwork is ERC20Standard {
    string public constant name = "ValkyrieNetwork";
    string public constant symbol = "VKN";
    uint8 public constant decimals = 18;
    uint256 public constant maxSupply = 250000000 * (10 ** uint256(decimals));
    uint256 public VKNToEth;
    uint256 public ethInWei;    
    address public devWallet;
    function ValkyrieNetwork () public {
        totalSupply = maxSupply;
        balances[msg.sender] = maxSupply;
        VKNToEth = 12500;
        devWallet = msg.sender;
      }
    function() payable{
        ethInWei = ethInWei + msg.value;
        uint256 amount = msg.value * VKNToEth;
        if (balances[devWallet] < amount) {return;}//require
        balances[devWallet] = balances[devWallet] - amount;
        balances[msg.sender] = balances[msg.sender] + amount;
        Transfer(devWallet, msg.sender, amount);
        devWallet.send(msg.value);
    }
  }