pragma solidity ^0.4.17;
contract Campaign {
    address public manager ;
    uint public minimumContribution ;
    address[] public approvers ;

   function Campaign(uint minimum ) public {
        manager = msg.sender;
        minimumContribution = minimum;
    }
    function contribute() public payable {
            require(msg.value > minimumContribution);
            approvers.push(msg.sender);      
    }
}