#
# This program finds the average of the inputed numbers.
#   Uses sentinel approach.
#   A sentinel here is an empty string
#

def main():
    print("This program finds the average of inputed numbers")

    sum_ = 0 # the sum of provided values
    counter = 0 # counter for the number of provided values
    ns='0' # values entered by the user are referenced to by next_value

    try:

        while ns != "": # termination condition: no value provided
            sum_ = sum_ + float(ns) # adding the provided value to the sum
            counter = counter+1 # incrementing the number of added values
            ns = input("Please, input a number (press <Enter> to stop):")
    except:
        print("Incorrect input.")

    if counter > 1:

        average = float(sum_)/(counter-1) # average
        print("The average of the entered numbers, rounded off to the nearest hundrendth,\
        is {0:0.2f}".format(average))


main()