import java.io.*;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        int n;

        while(true){
            n = Integer.parseInt(br.readLine());
            if(n == 0){
                break;
            }

            String[] str = br.readLine().split(" ");
            double ave = 0;
            double alpha = 0;
            double[] line = new double[n];
            for(int i = 0; i < n; i++){
                line[i] = Double.parseDouble(str[i]);
                ave += line[i];
            }
            ave /= n;

            for(int i = 0; i < n; i++){
                alpha += Math.pow((line[i]-ave), 2);
            }
            alpha /= n;
            sb.append(Math.sqrt(alpha)).append("\n");
        }
        System.out.print(sb.toString());
    }
} import java.io.*; io.* java public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        int n;

        while(true){
            n = Integer.parseInt(br.readLine());
            if(n == 0){
                break;
            }

            String[] str = br.readLine().split(" ");
            double ave = 0;
            double alpha = 0;
            double[] line = new double[n];
            for(int i = 0; i < n; i++){
                line[i] = Double.parseDouble(str[i]);
                ave += line[i];
            }
            ave /= n;

            for(int i = 0; i < n; i++){
                alpha += Math.pow((line[i]-ave), 2);
            }
            alpha /= n;
            sb.append(Math.sqrt(alpha)).append("\n");
        }
        System.out.print(sb.toString());
    }
} Main public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        int n;

        while(true){
            n = Integer.parseInt(br.readLine());
            if(n == 0){
                break;
            }

            String[] str = br.readLine().split(" ");
            double ave = 0;
            double alpha = 0;
            double[] line = new double[n];
            for(int i = 0; i < n; i++){
                line[i] = Double.parseDouble(str[i]);
                ave += line[i];
            }
            ave /= n;

            for(int i = 0; i < n; i++){
                alpha += Math.pow((line[i]-ave), 2);
            }
            alpha /= n;
            sb.append(Math.sqrt(alpha)).append("\n");
        }
        System.out.print(sb.toString());
    } main {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        int n;

        while(true){
            n = Integer.parseInt(br.readLine());
            if(n == 0){
                break;
            }

            String[] str = br.readLine().split(" ");
            double ave = 0;
            double alpha = 0;
            double[] line = new double[n];
            for(int i = 0; i < n; i++){
                line[i] = Double.parseDouble(str[i]);
                ave += line[i];
            }
            ave /= n;

            for(int i = 0; i < n; i++){
                alpha += Math.pow((line[i]-ave), 2);
            }
            alpha /= n;
            sb.append(Math.sqrt(alpha)).append("\n");
        }
        System.out.print(sb.toString());
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) StringBuilder sb = new StringBuilder(); sb new StringBuilder() int n; n while(true){
            n = Integer.parseInt(br.readLine());
            if(n == 0){
                break;
            }

            String[] str = br.readLine().split(" ");
            double ave = 0;
            double alpha = 0;
            double[] line = new double[n];
            for(int i = 0; i < n; i++){
                line[i] = Double.parseDouble(str[i]);
                ave += line[i];
            }
            ave /= n;

            for(int i = 0; i < n; i++){
                alpha += Math.pow((line[i]-ave), 2);
            }
            alpha /= n;
            sb.append(Math.sqrt(alpha)).append("\n");
        } true {
            n = Integer.parseInt(br.readLine());
            if(n == 0){
                break;
            }

            String[] str = br.readLine().split(" ");
            double ave = 0;
            double alpha = 0;
            double[] line = new double[n];
            for(int i = 0; i < n; i++){
                line[i] = Double.parseDouble(str[i]);
                ave += line[i];
            }
            ave /= n;

            for(int i = 0; i < n; i++){
                alpha += Math.pow((line[i]-ave), 2);
            }
            alpha /= n;
            sb.append(Math.sqrt(alpha)).append("\n");
        } n = Integer.parseInt(br.readLine()) n Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br if(n == 0){
                break;
            } n == 0 n 0 {
                break;
            } break; String[] str = br.readLine().split(" "); str br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " double ave = 0; ave 0 double alpha = 0; alpha 0 double[] line = new double[n]; line new double[n] n for(int i = 0; i < n; i++){
                line[i] = Double.parseDouble(str[i]);
                ave += line[i];
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                line[i] = Double.parseDouble(str[i]);
                ave += line[i];
            } {
                line[i] = Double.parseDouble(str[i]);
                ave += line[i];
            } line[i] = Double.parseDouble(str[i]) line[i] line i Double.parseDouble(str[i]) Double.parseDouble Double str[i] str i ave += line[i] ave line[i] line i ave /= n ave n for(int i = 0; i < n; i++){
                alpha += Math.pow((line[i]-ave), 2);
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                alpha += Math.pow((line[i]-ave), 2);
            } {
                alpha += Math.pow((line[i]-ave), 2);
            } alpha += Math.pow((line[i]-ave), 2) alpha Math.pow((line[i]-ave), 2) Math.pow Math (line[i]-ave) line[i] line i ave 2 alpha /= n alpha n sb.append(Math.sqrt(alpha)).append("\n") sb.append(Math.sqrt(alpha)).append sb.append(Math.sqrt(alpha)) sb.append sb Math.sqrt(alpha) Math.sqrt Math alpha "\n" System.out.print(sb.toString()) System.out.print System.out System System.out sb.toString() sb.toString sb String[] args args public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        int n;

        while(true){
            n = Integer.parseInt(br.readLine());
            if(n == 0){
                break;
            }

            String[] str = br.readLine().split(" ");
            double ave = 0;
            double alpha = 0;
            double[] line = new double[n];
            for(int i = 0; i < n; i++){
                line[i] = Double.parseDouble(str[i]);
                ave += line[i];
            }
            ave /= n;

            for(int i = 0; i < n; i++){
                alpha += Math.pow((line[i]-ave), 2);
            }
            alpha /= n;
            sb.append(Math.sqrt(alpha)).append("\n");
        }
        System.out.print(sb.toString());
    }
} public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        int n;

        while(true){
            n = Integer.parseInt(br.readLine());
            if(n == 0){
                break;
            }

            String[] str = br.readLine().split(" ");
            double ave = 0;
            double alpha = 0;
            double[] line = new double[n];
            for(int i = 0; i < n; i++){
                line[i] = Double.parseDouble(str[i]);
                ave += line[i];
            }
            ave /= n;

            for(int i = 0; i < n; i++){
                alpha += Math.pow((line[i]-ave), 2);
            }
            alpha /= n;
            sb.append(Math.sqrt(alpha)).append("\n");
        }
        System.out.print(sb.toString());
    }
} Main
import java.io.*;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        int n;

        while(true){
            n = Integer.parseInt(br.readLine());
            if(n == 0){
                break;
            }

            String[] str = br.readLine().split(" ");
            double ave = 0;
            double alpha = 0;
            double[] line = new double[n];
            for(int i = 0; i < n; i++){
                line[i] = Double.parseDouble(str[i]);
                ave += line[i];
            }
            ave /= n;

            for(int i = 0; i < n; i++){
                alpha += Math.pow((line[i]-ave), 2);
            }
            alpha /= n;
            sb.append(Math.sqrt(alpha)).append("\n");
        }
        System.out.print(sb.toString());
    }
}