def fibonacci():
    a, b = 1, 1
    while True:
        yield a
        a, b = b, a + b

def target_sum(limit, match):
    total = 0
    for x in fibonacci():
        if x >= limit:
            break
        if match(x):
            total += x
    return total

print(target_sum(4000000, lambda x: not (x & 1)))