# This lets the user enter numbers,
# until the user enters a negative.
# The program prints the average of those
# numbers.

done = False
sum = 0
count = 0
while not done:
    x = eval(input( "Number? " ))
    if x < 0:
        done = True
    else:
        sum = sum + x
        count = count + 1

print( "The average is %.5f"%(sum/count) )