import java.util.Scanner;
public class Main {
public static void main(String[] args) {
// 標準入力からデータを読み込む準備
try (Scanner sc = new Scanner(System.in)) {
while (true) {
int n = sc.nextInt();
if (n == 0) { break; }
int[] scores = new int[n];
for (int i = 0; i < scores.length; i++) {
scores[i] = sc.nextInt();
}
double average = 0, variance = 0;
// … 平均値averageと，分散varianceを計算しよう …
for(int i=0;i<scores.length;i++)average+=scores[i];
average/=n;
for(int i=0;i<scores.length;i++){
    variance+=Math.pow(scores[i]-average,2);
}
variance/=n;
System.out.println(Math.sqrt(variance));
}
}
}
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz