import java.util.Scanner;

public class Main {
    public static void main (String[] args) {
        Scanner scan = new Scanner(System.in);

        while(true){
            int n = scan.nextInt();
            if(n == 0){
                break;
            }
            int[] array_s = new int[n];
            int sum = 0;
            double v_2 = 0;
            double a;
            for(int i = 0; i < n; i++){
                array_s[i] = scan.nextInt();
                sum += array_s[i];
            }

            double m = (double)sum/(double)n;

            for(int i = 0; i < n; i++){
                v_2 += Math.pow(array_s[i]-m, 2);
            }

            a = Math.sqrt(v_2/n);
            System.out.println(a);
        }

    }
}
 import java.util.Scanner; Scanner java.util public class Main {
    public static void main (String[] args) {
        Scanner scan = new Scanner(System.in);

        while(true){
            int n = scan.nextInt();
            if(n == 0){
                break;
            }
            int[] array_s = new int[n];
            int sum = 0;
            double v_2 = 0;
            double a;
            for(int i = 0; i < n; i++){
                array_s[i] = scan.nextInt();
                sum += array_s[i];
            }

            double m = (double)sum/(double)n;

            for(int i = 0; i < n; i++){
                v_2 += Math.pow(array_s[i]-m, 2);
            }

            a = Math.sqrt(v_2/n);
            System.out.println(a);
        }

    }
} Main public static void main (String[] args) {
        Scanner scan = new Scanner(System.in);

        while(true){
            int n = scan.nextInt();
            if(n == 0){
                break;
            }
            int[] array_s = new int[n];
            int sum = 0;
            double v_2 = 0;
            double a;
            for(int i = 0; i < n; i++){
                array_s[i] = scan.nextInt();
                sum += array_s[i];
            }

            double m = (double)sum/(double)n;

            for(int i = 0; i < n; i++){
                v_2 += Math.pow(array_s[i]-m, 2);
            }

            a = Math.sqrt(v_2/n);
            System.out.println(a);
        }

    } main {
        Scanner scan = new Scanner(System.in);

        while(true){
            int n = scan.nextInt();
            if(n == 0){
                break;
            }
            int[] array_s = new int[n];
            int sum = 0;
            double v_2 = 0;
            double a;
            for(int i = 0; i < n; i++){
                array_s[i] = scan.nextInt();
                sum += array_s[i];
            }

            double m = (double)sum/(double)n;

            for(int i = 0; i < n; i++){
                v_2 += Math.pow(array_s[i]-m, 2);
            }

            a = Math.sqrt(v_2/n);
            System.out.println(a);
        }

    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) while(true){
            int n = scan.nextInt();
            if(n == 0){
                break;
            }
            int[] array_s = new int[n];
            int sum = 0;
            double v_2 = 0;
            double a;
            for(int i = 0; i < n; i++){
                array_s[i] = scan.nextInt();
                sum += array_s[i];
            }

            double m = (double)sum/(double)n;

            for(int i = 0; i < n; i++){
                v_2 += Math.pow(array_s[i]-m, 2);
            }

            a = Math.sqrt(v_2/n);
            System.out.println(a);
        } true {
            int n = scan.nextInt();
            if(n == 0){
                break;
            }
            int[] array_s = new int[n];
            int sum = 0;
            double v_2 = 0;
            double a;
            for(int i = 0; i < n; i++){
                array_s[i] = scan.nextInt();
                sum += array_s[i];
            }

            double m = (double)sum/(double)n;

            for(int i = 0; i < n; i++){
                v_2 += Math.pow(array_s[i]-m, 2);
            }

            a = Math.sqrt(v_2/n);
            System.out.println(a);
        } int n = scan.nextInt(); n scan.nextInt() scan.nextInt scan if(n == 0){
                break;
            } n == 0 n 0 {
                break;
            } break; int[] array_s = new int[n]; array_s new int[n] n int sum = 0; sum 0 double v_2 = 0; v_2 0 double a; a for(int i = 0; i < n; i++){
                array_s[i] = scan.nextInt();
                sum += array_s[i];
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                array_s[i] = scan.nextInt();
                sum += array_s[i];
            } {
                array_s[i] = scan.nextInt();
                sum += array_s[i];
            } array_s[i] = scan.nextInt() array_s[i] array_s i scan.nextInt() scan.nextInt scan sum += array_s[i] sum array_s[i] array_s i double m = (double)sum/(double)n; m (double)sum/(double)n (double)sum (double)n for(int i = 0; i < n; i++){
                v_2 += Math.pow(array_s[i]-m, 2);
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                v_2 += Math.pow(array_s[i]-m, 2);
            } {
                v_2 += Math.pow(array_s[i]-m, 2);
            } v_2 += Math.pow(array_s[i]-m, 2) v_2 Math.pow(array_s[i]-m, 2) Math.pow Math array_s[i]-m array_s[i] array_s i m 2 a = Math.sqrt(v_2/n) a Math.sqrt(v_2/n) Math.sqrt Math v_2/n v_2 n System.out.println(a) System.out.println System.out System System.out a String[] args args public class Main {
    public static void main (String[] args) {
        Scanner scan = new Scanner(System.in);

        while(true){
            int n = scan.nextInt();
            if(n == 0){
                break;
            }
            int[] array_s = new int[n];
            int sum = 0;
            double v_2 = 0;
            double a;
            for(int i = 0; i < n; i++){
                array_s[i] = scan.nextInt();
                sum += array_s[i];
            }

            double m = (double)sum/(double)n;

            for(int i = 0; i < n; i++){
                v_2 += Math.pow(array_s[i]-m, 2);
            }

            a = Math.sqrt(v_2/n);
            System.out.println(a);
        }

    }
} public class Main {
    public static void main (String[] args) {
        Scanner scan = new Scanner(System.in);

        while(true){
            int n = scan.nextInt();
            if(n == 0){
                break;
            }
            int[] array_s = new int[n];
            int sum = 0;
            double v_2 = 0;
            double a;
            for(int i = 0; i < n; i++){
                array_s[i] = scan.nextInt();
                sum += array_s[i];
            }

            double m = (double)sum/(double)n;

            for(int i = 0; i < n; i++){
                v_2 += Math.pow(array_s[i]-m, 2);
            }

            a = Math.sqrt(v_2/n);
            System.out.println(a);
        }

    }
} Main
import java.util.Scanner;

public class Main {
    public static void main (String[] args) {
        Scanner scan = new Scanner(System.in);

        while(true){
            int n = scan.nextInt();
            if(n == 0){
                break;
            }
            int[] array_s = new int[n];
            int sum = 0;
            double v_2 = 0;
            double a;
            for(int i = 0; i < n; i++){
                array_s[i] = scan.nextInt();
                sum += array_s[i];
            }

            double m = (double)sum/(double)n;

            for(int i = 0; i < n; i++){
                v_2 += Math.pow(array_s[i]-m, 2);
            }

            a = Math.sqrt(v_2/n);
            System.out.println(a);
        }

    }
}

