import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

    public static void main(String[] args) throws NumberFormatException, IOException {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        while(true){

            double total = 0;
            double average = 0;
            double a = 0;

            int n = Integer.parseInt(br.readLine());

//          ???????????¶
            if(n == 0){
                break;
            }
            String[] score = br.readLine().split(" ");

//          ?????????????¨????total?????????
            for(int i = 0; i < n; i++){
                total += Double.parseDouble(score[i]);
            }
//          ??????????????????average?????????
            average = total / n;

//          ?¨??????????a?????????
            for(int i = 0; i < n; i++){
               a += Math.pow(Double.parseDouble(score[i]) - average, 2);
            }
            a = Math.sqrt(Math.abs(a / n));

            System.out.println(a);
        }
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {

    public static void main(String[] args) throws NumberFormatException, IOException {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        while(true){

            double total = 0;
            double average = 0;
            double a = 0;

            int n = Integer.parseInt(br.readLine());

//          ???????????¶
            if(n == 0){
                break;
            }
            String[] score = br.readLine().split(" ");

//          ?????????????¨????total?????????
            for(int i = 0; i < n; i++){
                total += Double.parseDouble(score[i]);
            }
//          ??????????????????average?????????
            average = total / n;

//          ?¨??????????a?????????
            for(int i = 0; i < n; i++){
               a += Math.pow(Double.parseDouble(score[i]) - average, 2);
            }
            a = Math.sqrt(Math.abs(a / n));

            System.out.println(a);
        }
    }
} Main public static void main(String[] args) throws NumberFormatException, IOException {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        while(true){

            double total = 0;
            double average = 0;
            double a = 0;

            int n = Integer.parseInt(br.readLine());

//          ???????????¶
            if(n == 0){
                break;
            }
            String[] score = br.readLine().split(" ");

//          ?????????????¨????total?????????
            for(int i = 0; i < n; i++){
                total += Double.parseDouble(score[i]);
            }
//          ??????????????????average?????????
            average = total / n;

//          ?¨??????????a?????????
            for(int i = 0; i < n; i++){
               a += Math.pow(Double.parseDouble(score[i]) - average, 2);
            }
            a = Math.sqrt(Math.abs(a / n));

            System.out.println(a);
        }
    } main {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        while(true){

            double total = 0;
            double average = 0;
            double a = 0;

            int n = Integer.parseInt(br.readLine());

//          ???????????¶
            if(n == 0){
                break;
            }
            String[] score = br.readLine().split(" ");

//          ?????????????¨????total?????????
            for(int i = 0; i < n; i++){
                total += Double.parseDouble(score[i]);
            }
//          ??????????????????average?????????
            average = total / n;

//          ?¨??????????a?????????
            for(int i = 0; i < n; i++){
               a += Math.pow(Double.parseDouble(score[i]) - average, 2);
            }
            a = Math.sqrt(Math.abs(a / n));

            System.out.println(a);
        }
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) while(true){

            double total = 0;
            double average = 0;
            double a = 0;

            int n = Integer.parseInt(br.readLine());

//          ???????????¶
            if(n == 0){
                break;
            }
            String[] score = br.readLine().split(" ");

//          ?????????????¨????total?????????
            for(int i = 0; i < n; i++){
                total += Double.parseDouble(score[i]);
            }
//          ??????????????????average?????????
            average = total / n;

//          ?¨??????????a?????????
            for(int i = 0; i < n; i++){
               a += Math.pow(Double.parseDouble(score[i]) - average, 2);
            }
            a = Math.sqrt(Math.abs(a / n));

            System.out.println(a);
        } true {

            double total = 0;
            double average = 0;
            double a = 0;

            int n = Integer.parseInt(br.readLine());

//          ???????????¶
            if(n == 0){
                break;
            }
            String[] score = br.readLine().split(" ");

//          ?????????????¨????total?????????
            for(int i = 0; i < n; i++){
                total += Double.parseDouble(score[i]);
            }
//          ??????????????????average?????????
            average = total / n;

//          ?¨??????????a?????????
            for(int i = 0; i < n; i++){
               a += Math.pow(Double.parseDouble(score[i]) - average, 2);
            }
            a = Math.sqrt(Math.abs(a / n));

            System.out.println(a);
        } double total = 0; total 0 double average = 0; average 0 double a = 0; a 0 int 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[] score = br.readLine().split(" "); score br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " for(int i = 0; i < n; i++){
                total += Double.parseDouble(score[i]);
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                total += Double.parseDouble(score[i]);
            } {
                total += Double.parseDouble(score[i]);
            } total += Double.parseDouble(score[i]) total Double.parseDouble(score[i]) Double.parseDouble Double score[i] score i average = total / n average total / n total n for(int i = 0; i < n; i++){
               a += Math.pow(Double.parseDouble(score[i]) - average, 2);
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
               a += Math.pow(Double.parseDouble(score[i]) - average, 2);
            } {
               a += Math.pow(Double.parseDouble(score[i]) - average, 2);
            } a += Math.pow(Double.parseDouble(score[i]) - average, 2) a Math.pow(Double.parseDouble(score[i]) - average, 2) Math.pow Math Double.parseDouble(score[i]) - average Double.parseDouble(score[i]) Double.parseDouble Double score[i] score i average 2 a = Math.sqrt(Math.abs(a / n)) a Math.sqrt(Math.abs(a / n)) Math.sqrt Math Math.abs(a / n) Math.abs Math a / n a 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) throws NumberFormatException, IOException {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        while(true){

            double total = 0;
            double average = 0;
            double a = 0;

            int n = Integer.parseInt(br.readLine());

//          ???????????¶
            if(n == 0){
                break;
            }
            String[] score = br.readLine().split(" ");

//          ?????????????¨????total?????????
            for(int i = 0; i < n; i++){
                total += Double.parseDouble(score[i]);
            }
//          ??????????????????average?????????
            average = total / n;

//          ?¨??????????a?????????
            for(int i = 0; i < n; i++){
               a += Math.pow(Double.parseDouble(score[i]) - average, 2);
            }
            a = Math.sqrt(Math.abs(a / n));

            System.out.println(a);
        }
    }
} public class Main {

    public static void main(String[] args) throws NumberFormatException, IOException {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        while(true){

            double total = 0;
            double average = 0;
            double a = 0;

            int n = Integer.parseInt(br.readLine());

//          ???????????¶
            if(n == 0){
                break;
            }
            String[] score = br.readLine().split(" ");

//          ?????????????¨????total?????????
            for(int i = 0; i < n; i++){
                total += Double.parseDouble(score[i]);
            }
//          ??????????????????average?????????
            average = total / n;

//          ?¨??????????a?????????
            for(int i = 0; i < n; i++){
               a += Math.pow(Double.parseDouble(score[i]) - average, 2);
            }
            a = Math.sqrt(Math.abs(a / n));

            System.out.println(a);
        }
    }
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

    public static void main(String[] args) throws NumberFormatException, IOException {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        while(true){

            double total = 0;
            double average = 0;
            double a = 0;

            int n = Integer.parseInt(br.readLine());

//          ???????????¶
            if(n == 0){
                break;
            }
            String[] score = br.readLine().split(" ");

//          ?????????????¨????total?????????
            for(int i = 0; i < n; i++){
                total += Double.parseDouble(score[i]);
            }
//          ??????????????????average?????????
            average = total / n;

//          ?¨??????????a?????????
            for(int i = 0; i < n; i++){
               a += Math.pow(Double.parseDouble(score[i]) - average, 2);
            }
            a = Math.sqrt(Math.abs(a / n));

            System.out.println(a);
        }
    }
}