#!/usr/bin/env python
# encoding: utf-8


def problem2():
    """
    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.
    """
    x, y = 1, 2
    result = 0
    while True:
        x, y = y, x + y
        print x
        if(x > 4000000):
            break
        else:
            if(x % 2 == 0):
                result += x
    return result

if __name__ == "__main__":
    print problem2()
