import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n;
        while(true){
            n = sc.nextInt();
            if(n == 0){
                break;
            }

            int[] score = new int[n];
            int sum_1=0;
            for(int i=0;i<n;i++){
                score[i] = sc.nextInt();
                sum_1 += score[i];
            }

            
            double ave,sum_2=0,sd;
            ave = (double)sum_1/n;
            for(int i=0;i<n;i++){
                sum_2 += Math.pow((score[i]-ave),2);
            }
            sd = Math.sqrt((double)sum_2/n);
            System.out.printf("%.5f\n",sd);
        }
    }
}
 import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n;
        while(true){
            n = sc.nextInt();
            if(n == 0){
                break;
            }

            int[] score = new int[n];
            int sum_1=0;
            for(int i=0;i<n;i++){
                score[i] = sc.nextInt();
                sum_1 += score[i];
            }

            
            double ave,sum_2=0,sd;
            ave = (double)sum_1/n;
            for(int i=0;i<n;i++){
                sum_2 += Math.pow((score[i]-ave),2);
            }
            sd = Math.sqrt((double)sum_2/n);
            System.out.printf("%.5f\n",sd);
        }
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n;
        while(true){
            n = sc.nextInt();
            if(n == 0){
                break;
            }

            int[] score = new int[n];
            int sum_1=0;
            for(int i=0;i<n;i++){
                score[i] = sc.nextInt();
                sum_1 += score[i];
            }

            
            double ave,sum_2=0,sd;
            ave = (double)sum_1/n;
            for(int i=0;i<n;i++){
                sum_2 += Math.pow((score[i]-ave),2);
            }
            sd = Math.sqrt((double)sum_2/n);
            System.out.printf("%.5f\n",sd);
        }
    } main {
        Scanner sc = new Scanner(System.in);
        int n;
        while(true){
            n = sc.nextInt();
            if(n == 0){
                break;
            }

            int[] score = new int[n];
            int sum_1=0;
            for(int i=0;i<n;i++){
                score[i] = sc.nextInt();
                sum_1 += score[i];
            }

            
            double ave,sum_2=0,sd;
            ave = (double)sum_1/n;
            for(int i=0;i<n;i++){
                sum_2 += Math.pow((score[i]-ave),2);
            }
            sd = Math.sqrt((double)sum_2/n);
            System.out.printf("%.5f\n",sd);
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n; n while(true){
            n = sc.nextInt();
            if(n == 0){
                break;
            }

            int[] score = new int[n];
            int sum_1=0;
            for(int i=0;i<n;i++){
                score[i] = sc.nextInt();
                sum_1 += score[i];
            }

            
            double ave,sum_2=0,sd;
            ave = (double)sum_1/n;
            for(int i=0;i<n;i++){
                sum_2 += Math.pow((score[i]-ave),2);
            }
            sd = Math.sqrt((double)sum_2/n);
            System.out.printf("%.5f\n",sd);
        } true {
            n = sc.nextInt();
            if(n == 0){
                break;
            }

            int[] score = new int[n];
            int sum_1=0;
            for(int i=0;i<n;i++){
                score[i] = sc.nextInt();
                sum_1 += score[i];
            }

            
            double ave,sum_2=0,sd;
            ave = (double)sum_1/n;
            for(int i=0;i<n;i++){
                sum_2 += Math.pow((score[i]-ave),2);
            }
            sd = Math.sqrt((double)sum_2/n);
            System.out.printf("%.5f\n",sd);
        } n = sc.nextInt() n sc.nextInt() sc.nextInt sc if(n == 0){
                break;
            } n == 0 n 0 {
                break;
            } break; int[] score = new int[n]; score new int[n] n int sum_1=0; sum_1 0 for(int i=0;i<n;i++){
                score[i] = sc.nextInt();
                sum_1 += score[i];
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                score[i] = sc.nextInt();
                sum_1 += score[i];
            } {
                score[i] = sc.nextInt();
                sum_1 += score[i];
            } score[i] = sc.nextInt() score[i] score i sc.nextInt() sc.nextInt sc sum_1 += score[i] sum_1 score[i] score i double ave ave sum_2=0 sum_2 0 sd; sd ave = (double)sum_1/n ave (double)sum_1/n (double)sum_1 n for(int i=0;i<n;i++){
                sum_2 += Math.pow((score[i]-ave),2);
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                sum_2 += Math.pow((score[i]-ave),2);
            } {
                sum_2 += Math.pow((score[i]-ave),2);
            } sum_2 += Math.pow((score[i]-ave),2) sum_2 Math.pow((score[i]-ave),2) Math.pow Math (score[i]-ave) score[i] score i ave 2 sd = Math.sqrt((double)sum_2/n) sd Math.sqrt((double)sum_2/n) Math.sqrt Math (double)sum_2/n (double)sum_2 n System.out.printf("%.5f\n",sd) System.out.printf System.out System System.out "%.5f\n" sd String[] args args public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n;
        while(true){
            n = sc.nextInt();
            if(n == 0){
                break;
            }

            int[] score = new int[n];
            int sum_1=0;
            for(int i=0;i<n;i++){
                score[i] = sc.nextInt();
                sum_1 += score[i];
            }

            
            double ave,sum_2=0,sd;
            ave = (double)sum_1/n;
            for(int i=0;i<n;i++){
                sum_2 += Math.pow((score[i]-ave),2);
            }
            sd = Math.sqrt((double)sum_2/n);
            System.out.printf("%.5f\n",sd);
        }
    }
} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n;
        while(true){
            n = sc.nextInt();
            if(n == 0){
                break;
            }

            int[] score = new int[n];
            int sum_1=0;
            for(int i=0;i<n;i++){
                score[i] = sc.nextInt();
                sum_1 += score[i];
            }

            
            double ave,sum_2=0,sd;
            ave = (double)sum_1/n;
            for(int i=0;i<n;i++){
                sum_2 += Math.pow((score[i]-ave),2);
            }
            sd = Math.sqrt((double)sum_2/n);
            System.out.printf("%.5f\n",sd);
        }
    }
} Main
import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n;
        while(true){
            n = sc.nextInt();
            if(n == 0){
                break;
            }

            int[] score = new int[n];
            int sum_1=0;
            for(int i=0;i<n;i++){
                score[i] = sc.nextInt();
                sum_1 += score[i];
            }

            
            double ave,sum_2=0,sd;
            ave = (double)sum_1/n;
            for(int i=0;i<n;i++){
                sum_2 += Math.pow((score[i]-ave),2);
            }
            sd = Math.sqrt((double)sum_2/n);
            System.out.printf("%.5f\n",sd);
        }
    }
}

