import java.util.Scanner;
public class Main{
	public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int[] s = new int[n];
            int sum = 0;
            for(int i = 0; i < n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            double average = (double)sum / n;
            double variance = 0;
            for(int i = 0; i < n; i++){
                variance += (s[i] - average)*(s[i] - average)/n;
            }
            System.out.println((Math.sqrt(variance)));
        }
        sc.close();
    }
}
 import java.util.Scanner; Scanner java.util public class Main{
	public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int[] s = new int[n];
            int sum = 0;
            for(int i = 0; i < n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            double average = (double)sum / n;
            double variance = 0;
            for(int i = 0; i < n; i++){
                variance += (s[i] - average)*(s[i] - average)/n;
            }
            System.out.println((Math.sqrt(variance)));
        }
        sc.close();
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int[] s = new int[n];
            int sum = 0;
            for(int i = 0; i < n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            double average = (double)sum / n;
            double variance = 0;
            for(int i = 0; i < n; i++){
                variance += (s[i] - average)*(s[i] - average)/n;
            }
            System.out.println((Math.sqrt(variance)));
        }
        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int[] s = new int[n];
            int sum = 0;
            for(int i = 0; i < n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            double average = (double)sum / n;
            double variance = 0;
            for(int i = 0; i < n; i++){
                variance += (s[i] - average)*(s[i] - average)/n;
            }
            System.out.println((Math.sqrt(variance)));
        }
        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int[] s = new int[n];
            int sum = 0;
            for(int i = 0; i < n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            double average = (double)sum / n;
            double variance = 0;
            for(int i = 0; i < n; i++){
                variance += (s[i] - average)*(s[i] - average)/n;
            }
            System.out.println((Math.sqrt(variance)));
        } true {
            int n = sc.nextInt();
            if(n == 0) break;
            int[] s = new int[n];
            int sum = 0;
            for(int i = 0; i < n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            double average = (double)sum / n;
            double variance = 0;
            for(int i = 0; i < n; i++){
                variance += (s[i] - average)*(s[i] - average)/n;
            }
            System.out.println((Math.sqrt(variance)));
        } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n == 0) break; n == 0 n 0 break; int[] s = new int[n]; s new int[n] n int sum = 0; sum 0 for(int i = 0; i < n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                s[i] = sc.nextInt();
                sum += s[i];
            } {
                s[i] = sc.nextInt();
                sum += s[i];
            } s[i] = sc.nextInt() s[i] s i sc.nextInt() sc.nextInt sc sum += s[i] sum s[i] s i double average = (double)sum / n; average (double)sum / n (double)sum n double variance = 0; variance 0 for(int i = 0; i < n; i++){
                variance += (s[i] - average)*(s[i] - average)/n;
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                variance += (s[i] - average)*(s[i] - average)/n;
            } {
                variance += (s[i] - average)*(s[i] - average)/n;
            } variance += (s[i] - average)*(s[i] - average)/n variance (s[i] - average)*(s[i] - average)/n (s[i] - average)*(s[i] - average) (s[i] - average) s[i] s i average (s[i] - average) s[i] s i average n System.out.println((Math.sqrt(variance))) System.out.println System.out System System.out (Math.sqrt(variance)) Math.sqrt Math variance sc.close() sc.close sc String[] args args public class Main{
	public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int[] s = new int[n];
            int sum = 0;
            for(int i = 0; i < n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            double average = (double)sum / n;
            double variance = 0;
            for(int i = 0; i < n; i++){
                variance += (s[i] - average)*(s[i] - average)/n;
            }
            System.out.println((Math.sqrt(variance)));
        }
        sc.close();
    }
} public class Main{
	public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int[] s = new int[n];
            int sum = 0;
            for(int i = 0; i < n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            double average = (double)sum / n;
            double variance = 0;
            for(int i = 0; i < n; i++){
                variance += (s[i] - average)*(s[i] - average)/n;
            }
            System.out.println((Math.sqrt(variance)));
        }
        sc.close();
    }
} Main
import java.util.Scanner;
public class Main{
	public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n == 0) break;
            int[] s = new int[n];
            int sum = 0;
            for(int i = 0; i < n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            double average = (double)sum / n;
            double variance = 0;
            for(int i = 0; i < n; i++){
                variance += (s[i] - average)*(s[i] - average)/n;
            }
            System.out.println((Math.sqrt(variance)));
        }
        sc.close();
    }
}

