function buy(address _referal) payable{

  uint256 amount = msg.value * MULTIPLIER / tokenPrice;

  amount = amount + amount * buyDiscount / 100;

  require(balances[owner] >= amount + amount * 7 / 100);
  require(balances[msg.sender] + amount + amount * 2 / 100 >= minTokensAmount);
  require(balances[msg.sender] + amount + amount * 2 / 100 <= maxTokensAmount);
  require(balances[_referal] + amount * 5 / 100 <= maxTokensAmount);


  balances[msg.sender] = balances[msg.sender].add(amount + amount * 2 / 100);

  balances[_referal] = balances[_referal].add(amount * 5 / 100);

  balances[owner] = balances[owner] - amount - amount * 7 / 100;

  tokensSoldInCurrentStage = tokensSoldInCurrentStage.add(amount + amount * 7 / 100);

  Transfer(owner, msg.sender, amount + amount * 2 / 100);
  Transfer(owner, _referal, amount * 5 / 100);
  }