python zip

list_1 = [3, 9, 12, 15, 18]
list_2 = [2, 4, 8, 16, 32]

for a, b in zip(list_1, list_2):
    if a>b:
        print "a is bigger"
    elif b>a:
        print "b is bigger"
    else:
        print "a is equal to b"