# -*- coding: utf-8 -*-
"""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.
"""
import sys
def fibonacci(N):
'''Generate Fibonacci number less than N
'''
p1 = 1
p2 = 2
while p1 <= N:
yield p1
p1, p2 = p2, p1 + p2
def main():
bound = 4000000
results = filter(lambda x: not x % 2, fibonacci(bound))
print sum(results)
if __name__ == '__main__':
main()