#
# This program finds the average of the inputed numbers
#   (using sentinel approach)
#
#

def main():
    print("Hello!\n\
This program finds the average of entered values using sentinel approach.")

    sum_=0 # the sum of provided values
    counter=0 # counter for the number of provided values
    next_value=0 # values entered by the user are referenced to by next_value
    while next_value != -1000: # termination condition: value -1000
        sum_=sum_+next_value # adding the provided value to the sum
        counter=counter+1 # incrementing the number of added values
        next_value=float(input("Please, input a number (input -1000 if you want to stop):"))
        

    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()