let lastTwo = [0, 1];
let sum = 0;
loop forever {
    let last = lastTwo[1];
    let current = lastTwo[0] + last;
    if current > 4000000 {
        break;
    }
    if current % 2 == 0 {
        sum = sum + current;
    }
    lastTwo = [last, current];
}
println(sum);