# Returns the first even number in the given list,
# or None if no such string is found.
def shortest_plural(words):
    for s in words:
        if n % 2 == 0:
            return n
    return None

def main():
    numbers = [3, 19, 42, -1, 28, 0, 56]
    even = first_even(numbers)
    print("First even number is", even)

    numbers = [3, 19, 45, -1, 27, 51]
    even = first_even(numbers)
    print("First even number is", even)

main()