contract Investors {

    address[] public investors;
    mapping(address => uint) investorIndex;

    /**
     * @dev Contructor that authorizes the msg.sender.
     */
    function Investors() public {
        investors.length = 2;
        investors[1] = msg.sender;
        investorIndex[msg.sender] = 1;
    }

    /**
     * @dev Function to add a new investor
     * @param _inv the address to add as a new investor.
     */
    function addInvestor(address _inv) public {
        if (investorIndex[_inv] <= 0) {
            investorIndex[_inv] = investors.length;
            investors.length++;
            investors[investors.length - 1] = _inv;
        }

    }
}
function Investors() public {
    investors.length = 2;
    investors[1] = msg.sender;
    investorIndex[msg.sender] = 1;
}

/**
 * @dev Contructor that authorizes the msg.sender.
 */