import statistics

while True:

    n = eval(input())

    if n == '0': break

    print((statistics.pstdev(list(map(int, input().split())))))
import math



while True:

    n = int(eval(input()))

    if n == 0:

        break

    points = list(map(int, input().split()))



    m = sum(points) / n

    variance = sum([(x - m) ** 2 for x in points]) / n

    standard_deviation = math.sqrt(variance)

    print(standard_deviation)



import statistics

while True:
    n = eval(input())
    if n == "0":
        break
    print((statistics.pstdev(list(map(int, input().split())))))

import math

while True:
    n = int(eval(input()))
    if n == 0:
        break
    points = list(map(int, input().split()))
    m = sum(points) / n
    variance = sum([(x - m) ** 2 for x in points]) / n
    standard_deviation = math.sqrt(variance)
    print(standard_deviation)

-import statistics +import math -    n = eval(input()) -    if n == "0": +    n = int(eval(input())) +    if n == 0: -    print((statistics.pstdev(list(map(int, input().split()))))) +    points = list(map(int, input().split())) +    m = sum(points) / n +    variance = sum([(x - m) ** 2 for x in points]) / n +    standard_deviation = math.sqrt(variance) +    print(standard_deviation)