import time

start = time.time()
Fn_1 = 1
Fn  = 2
fib_sum = 0
while(Fn < 4e6):
    if Fn%2==0:
        fib_sum += Fn
    Fn, Fn_1 = Fn+Fn_1, Fn 

print "Answer:{}".format( fib_sum )
print "Elapsed time:{0} seconds".format(time.time()-start)