
import java.util.Random;
import java.util.Scanner;

public class Main{
    public static void main(final String[] args){
        Scanner scanner = new Scanner(System.in);
        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
            }
            int[] s = new int[n] ;
            for (int i = 0; i < n; i++){
                s[i] = scanner.nextInt();
            }
            int sum = 0;
            for(int i = 0; i < n; i++){
                sum += s[i];
            }
            double ave = (double)sum / (double)n;
            double sum2 = 0;
            for(int i = 0; i < n; i++){
                sum2 += Math.pow((double)s[i], 2);
            }
            double ave2 = sum2/(double)n;
            double v = ave2 - Math.pow(ave, 2);
            System.out.println(Math.sqrt(v));
        }
        scanner.close();
    }
     
    

} import java.util.Random; Random java.util import java.util.Scanner; Scanner java.util public class Main{
    public static void main(final String[] args){
        Scanner scanner = new Scanner(System.in);
        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
            }
            int[] s = new int[n] ;
            for (int i = 0; i < n; i++){
                s[i] = scanner.nextInt();
            }
            int sum = 0;
            for(int i = 0; i < n; i++){
                sum += s[i];
            }
            double ave = (double)sum / (double)n;
            double sum2 = 0;
            for(int i = 0; i < n; i++){
                sum2 += Math.pow((double)s[i], 2);
            }
            double ave2 = sum2/(double)n;
            double v = ave2 - Math.pow(ave, 2);
            System.out.println(Math.sqrt(v));
        }
        scanner.close();
    }
     
    

} Main public static void main(final String[] args){
        Scanner scanner = new Scanner(System.in);
        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
            }
            int[] s = new int[n] ;
            for (int i = 0; i < n; i++){
                s[i] = scanner.nextInt();
            }
            int sum = 0;
            for(int i = 0; i < n; i++){
                sum += s[i];
            }
            double ave = (double)sum / (double)n;
            double sum2 = 0;
            for(int i = 0; i < n; i++){
                sum2 += Math.pow((double)s[i], 2);
            }
            double ave2 = sum2/(double)n;
            double v = ave2 - Math.pow(ave, 2);
            System.out.println(Math.sqrt(v));
        }
        scanner.close();
    } main {
        Scanner scanner = new Scanner(System.in);
        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
            }
            int[] s = new int[n] ;
            for (int i = 0; i < n; i++){
                s[i] = scanner.nextInt();
            }
            int sum = 0;
            for(int i = 0; i < n; i++){
                sum += s[i];
            }
            double ave = (double)sum / (double)n;
            double sum2 = 0;
            for(int i = 0; i < n; i++){
                sum2 += Math.pow((double)s[i], 2);
            }
            double ave2 = sum2/(double)n;
            double v = ave2 - Math.pow(ave, 2);
            System.out.println(Math.sqrt(v));
        }
        scanner.close();
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
            }
            int[] s = new int[n] ;
            for (int i = 0; i < n; i++){
                s[i] = scanner.nextInt();
            }
            int sum = 0;
            for(int i = 0; i < n; i++){
                sum += s[i];
            }
            double ave = (double)sum / (double)n;
            double sum2 = 0;
            for(int i = 0; i < n; i++){
                sum2 += Math.pow((double)s[i], 2);
            }
            double ave2 = sum2/(double)n;
            double v = ave2 - Math.pow(ave, 2);
            System.out.println(Math.sqrt(v));
        } true {
            int n = scanner.nextInt();
            if(n == 0){
                break;
            }
            int[] s = new int[n] ;
            for (int i = 0; i < n; i++){
                s[i] = scanner.nextInt();
            }
            int sum = 0;
            for(int i = 0; i < n; i++){
                sum += s[i];
            }
            double ave = (double)sum / (double)n;
            double sum2 = 0;
            for(int i = 0; i < n; i++){
                sum2 += Math.pow((double)s[i], 2);
            }
            double ave2 = sum2/(double)n;
            double v = ave2 - Math.pow(ave, 2);
            System.out.println(Math.sqrt(v));
        } int n = scanner.nextInt(); n scanner.nextInt() scanner.nextInt scanner if(n == 0){
                break;
            } n == 0 n 0 {
                break;
            } break; int[] s = new int[n] ; s new int[n] n for (int i = 0; i < n; i++){
                s[i] = scanner.nextInt();
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                s[i] = scanner.nextInt();
            } {
                s[i] = scanner.nextInt();
            } s[i] = scanner.nextInt() s[i] s i scanner.nextInt() scanner.nextInt scanner int sum = 0; sum 0 for(int i = 0; i < n; i++){
                sum += s[i];
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                sum += s[i];
            } {
                sum += s[i];
            } sum += s[i] sum s[i] s i double ave = (double)sum / (double)n; ave (double)sum / (double)n (double)sum (double)n double sum2 = 0; sum2 0 for(int i = 0; i < n; i++){
                sum2 += Math.pow((double)s[i], 2);
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                sum2 += Math.pow((double)s[i], 2);
            } {
                sum2 += Math.pow((double)s[i], 2);
            } sum2 += Math.pow((double)s[i], 2) sum2 Math.pow((double)s[i], 2) Math.pow Math (double)s[i] s i 2 double ave2 = sum2/(double)n; ave2 sum2/(double)n sum2 (double)n double v = ave2 - Math.pow(ave, 2); v ave2 - Math.pow(ave, 2) ave2 Math.pow(ave, 2) Math.pow Math ave 2 System.out.println(Math.sqrt(v)) System.out.println System.out System System.out Math.sqrt(v) Math.sqrt Math v scanner.close() scanner.close scanner final String[] args args public class Main{
    public static void main(final String[] args){
        Scanner scanner = new Scanner(System.in);
        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
            }
            int[] s = new int[n] ;
            for (int i = 0; i < n; i++){
                s[i] = scanner.nextInt();
            }
            int sum = 0;
            for(int i = 0; i < n; i++){
                sum += s[i];
            }
            double ave = (double)sum / (double)n;
            double sum2 = 0;
            for(int i = 0; i < n; i++){
                sum2 += Math.pow((double)s[i], 2);
            }
            double ave2 = sum2/(double)n;
            double v = ave2 - Math.pow(ave, 2);
            System.out.println(Math.sqrt(v));
        }
        scanner.close();
    }
     
    

} public class Main{
    public static void main(final String[] args){
        Scanner scanner = new Scanner(System.in);
        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
            }
            int[] s = new int[n] ;
            for (int i = 0; i < n; i++){
                s[i] = scanner.nextInt();
            }
            int sum = 0;
            for(int i = 0; i < n; i++){
                sum += s[i];
            }
            double ave = (double)sum / (double)n;
            double sum2 = 0;
            for(int i = 0; i < n; i++){
                sum2 += Math.pow((double)s[i], 2);
            }
            double ave2 = sum2/(double)n;
            double v = ave2 - Math.pow(ave, 2);
            System.out.println(Math.sqrt(v));
        }
        scanner.close();
    }
     
    

} Main

import java.util.Random;
import java.util.Scanner;

public class Main{
    public static void main(final String[] args){
        Scanner scanner = new Scanner(System.in);
        while(true){
            int n = scanner.nextInt();
            if(n == 0){
                break;
            }
            int[] s = new int[n] ;
            for (int i = 0; i < n; i++){
                s[i] = scanner.nextInt();
            }
            int sum = 0;
            for(int i = 0; i < n; i++){
                sum += s[i];
            }
            double ave = (double)sum / (double)n;
            double sum2 = 0;
            for(int i = 0; i < n; i++){
                sum2 += Math.pow((double)s[i], 2);
            }
            double ave2 = sum2/(double)n;
            double v = ave2 - Math.pow(ave, 2);
            System.out.println(Math.sqrt(v));
        }
        scanner.close();
    }
     
    

}
