pragma solidity ^0.4.18;

contract Ownable {
    address public owner;

    function Ownable() public {
        owner = msg.sender;
    }

    modifier onlyOwner() {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address newOwner) public onlyOwner {
        owner = newOwner;
    }
}

contract FinQueue is Ownable {
    uint256 public price = 1e17;
    uint256 public max_size = 2;

    function increasePrice() private {
        price = price*3/2;
    }

    function forReturn() private returns(uint256) {
        return price*4/5;
    }


    mapping (uint256 => address) queue;
    uint256 public curr = 0;
    uint256 public size = 0;

    function add() payable public {
        require(msg.value >= price);

        if (size == max_size) {
            address outer = queue[curr];
            outer.transfer(forReturn());
        }
        else {
            size++;
        }
        queue[curr] = msg.sender;
        curr = (curr + 1) % max_size;

        if (msg.value > price) {
            msg.sender.transfer(msg.value - price);
        }
        owner.transfer(this.balance);
    }
}