import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n;
        while ((n = scan.nextInt()) != 0) {
            int[] s = new int[n];
            double m = 0;
            for (int i = 0; i < n; i++) {
                s[i] = scan.nextInt();
                m += s[i];
            }
            m /= n;
            double sum = 0;
            for(int i = 0; i < s.length; i++){
            	sum += (s[i] - m) * (s[i] - m);
            }
            System.out.println(Math.sqrt(sum/n));
        }
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n;
        while ((n = scan.nextInt()) != 0) {
            int[] s = new int[n];
            double m = 0;
            for (int i = 0; i < n; i++) {
                s[i] = scan.nextInt();
                m += s[i];
            }
            m /= n;
            double sum = 0;
            for(int i = 0; i < s.length; i++){
            	sum += (s[i] - m) * (s[i] - m);
            }
            System.out.println(Math.sqrt(sum/n));
        }
    }
} Main public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n;
        while ((n = scan.nextInt()) != 0) {
            int[] s = new int[n];
            double m = 0;
            for (int i = 0; i < n; i++) {
                s[i] = scan.nextInt();
                m += s[i];
            }
            m /= n;
            double sum = 0;
            for(int i = 0; i < s.length; i++){
            	sum += (s[i] - m) * (s[i] - m);
            }
            System.out.println(Math.sqrt(sum/n));
        }
    } main {
        Scanner scan = new Scanner(System.in);
        int n;
        while ((n = scan.nextInt()) != 0) {
            int[] s = new int[n];
            double m = 0;
            for (int i = 0; i < n; i++) {
                s[i] = scan.nextInt();
                m += s[i];
            }
            m /= n;
            double sum = 0;
            for(int i = 0; i < s.length; i++){
            	sum += (s[i] - m) * (s[i] - m);
            }
            System.out.println(Math.sqrt(sum/n));
        }
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int n; n while ((n = scan.nextInt()) != 0) {
            int[] s = new int[n];
            double m = 0;
            for (int i = 0; i < n; i++) {
                s[i] = scan.nextInt();
                m += s[i];
            }
            m /= n;
            double sum = 0;
            for(int i = 0; i < s.length; i++){
            	sum += (s[i] - m) * (s[i] - m);
            }
            System.out.println(Math.sqrt(sum/n));
        } (n = scan.nextInt()) != 0 (n = scan.nextInt()) n scan.nextInt() scan.nextInt scan 0 {
            int[] s = new int[n];
            double m = 0;
            for (int i = 0; i < n; i++) {
                s[i] = scan.nextInt();
                m += s[i];
            }
            m /= n;
            double sum = 0;
            for(int i = 0; i < s.length; i++){
            	sum += (s[i] - m) * (s[i] - m);
            }
            System.out.println(Math.sqrt(sum/n));
        } int[] s = new int[n]; s new int[n] n double m = 0; m 0 for (int i = 0; i < n; i++) {
                s[i] = scan.nextInt();
                m += s[i];
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                s[i] = scan.nextInt();
                m += s[i];
            } {
                s[i] = scan.nextInt();
                m += s[i];
            } s[i] = scan.nextInt() s[i] s i scan.nextInt() scan.nextInt scan m += s[i] m s[i] s i m /= n m n double sum = 0; sum 0 for(int i = 0; i < s.length; i++){
            	sum += (s[i] - m) * (s[i] - m);
            } int i = 0; int i = 0; i 0 i < s.length i s.length s s.length i++ i++ i {
            	sum += (s[i] - m) * (s[i] - m);
            } {
            	sum += (s[i] - m) * (s[i] - m);
            } sum += (s[i] - m) * (s[i] - m) sum (s[i] - m) * (s[i] - m) (s[i] - m) s[i] s i m (s[i] - m) s[i] s i m System.out.println(Math.sqrt(sum/n)) System.out.println System.out System System.out Math.sqrt(sum/n) Math.sqrt Math sum/n sum n String[] args args public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n;
        while ((n = scan.nextInt()) != 0) {
            int[] s = new int[n];
            double m = 0;
            for (int i = 0; i < n; i++) {
                s[i] = scan.nextInt();
                m += s[i];
            }
            m /= n;
            double sum = 0;
            for(int i = 0; i < s.length; i++){
            	sum += (s[i] - m) * (s[i] - m);
            }
            System.out.println(Math.sqrt(sum/n));
        }
    }
} public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n;
        while ((n = scan.nextInt()) != 0) {
            int[] s = new int[n];
            double m = 0;
            for (int i = 0; i < n; i++) {
                s[i] = scan.nextInt();
                m += s[i];
            }
            m /= n;
            double sum = 0;
            for(int i = 0; i < s.length; i++){
            	sum += (s[i] - m) * (s[i] - m);
            }
            System.out.println(Math.sqrt(sum/n));
        }
    }
} Main
import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n;
        while ((n = scan.nextInt()) != 0) {
            int[] s = new int[n];
            double m = 0;
            for (int i = 0; i < n; i++) {
                s[i] = scan.nextInt();
                m += s[i];
            }
            m /= n;
            double sum = 0;
            for(int i = 0; i < s.length; i++){
            	sum += (s[i] - m) * (s[i] - m);
            }
            System.out.println(Math.sqrt(sum/n));
        }
    }
}