// Each new term in the Fibonacci sequence is generated by adding the previous two terms. 
// By starting with 1 and 2, the first 10 terms will be:
//   1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
// By considering the terms in the Fibonacci sequence whose values do not exceed four million, 
// find the sum of the even-valued terms.
// 
// Correct Answer: 4613732

sum <- 0;

a <- 0;
b <- 1;
tmp <- 0;

loop a < 4_000_000 {
    if a % 2 == 0 {
        sum = sum + a;
    }

    tmp = a;
    a = b;
    b = b + tmp;
}

print sum;