#
# 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
    counter=0
    ns='0'
    while ns != "":
        sum_=sum_+eval(ns)
        counter=counter+1
        ns=raw_input("Please, input a number (press <Enter> to stop):")
        

    average=float(sum_)/(counter-1)
    print "The average of the inputed numbers is %0.2f" % average


main()