# Computes the average of the numbers in the given list.
# Example: average([1, 6, 2]) returns 3.0.
def average(numbers):
    sum = 0
    count = 0
    for n in numbers:
        sum += n
        count += 1
    return sum / count

def main():
    numbers = [1, 7, 3, 9]
    avg = average(numbers)
    print("average of", numbers, "is", avg)

main()