pragma solidity ^0.4.19;

contract ICO {
    address public owner;
    mapping(address => uint) public balances;
    address[] public buyers;

    uint constant public MULTIPLIER = 1000;

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

    function getBuyersLength() public constant returns (uint) {
        return buyers.length;
    }

    function buy() public payable {
        uint coins = msg.value * MULTIPLIER;
        balances[msg.sender] += coins;
        buyers.push(msg.sender);
    }
}

function main() {
    let contract = web3.eth.contract(CONTRACT_ABI).at(CONTRACT_ADDR);
    let amount = w3.toWei(10, 'ether');
    contract.buy({'value': amount}, function (err, res) {
        if (err) {
            console.error('Error occurred: ' + err);
        } else {
            console.log('Transaction created: ' + res);
        }
    })
}

function updateBalances() {
    contract.getBuyersLength(function (err, res) {
        if (err) {
            console.error('Error in getBuyers: ' + err);
        } else {
            console.log('Count of Buyers: ' + res);
        }
    }
}