# This program computes the average of a list of numbers given by the user.

def main():
    sum = 0.0
    count = 0
    done = False

    while not done:
        value = input( "Enter a number, or 0 to exit: " )
        sum = sum + value
        count = count + 1
        if value == 0:
            done = True
 
    print "%.2f" % (sum/count)       


main()