from statistics import pstdev

while True:

    data_count = int(eval(input()))

    if data_count == 0:

        break

    print((pstdev(int(x) for x in input().split())))

from statistics import pstdev

while True:

    data_count = int(eval(input()))

    if data_count == 0:

        break

    print((pstdev(list(map(int, input().split())))))

from statistics import pstdev

while True:
    data_count = int(eval(input()))
    if data_count == 0:
        break
    print((pstdev(int(x) for x in input().split())))

from statistics import pstdev

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

-    print((pstdev(int(x) for x in input().split()))) +    print((pstdev(list(map(int, input().split())))))