import java.util.Scanner;

public class Main{
    public static void main(String[]args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
            int sum=0;
            double sqsum=0;
            int n=sc.nextInt();
            if(n==0) break;
            int[] score = new int[n];
            for(int i=0;i<score.length;i++){
                score[i]=sc.nextInt();
                sum+=score[i];
                }
                double ave=0,bunsan=0;
                ave=(double) sum/n;
                for(int i=0;i<score.length;i++){
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                }
                bunsan=(double) sqsum/n;
                System.out.println(Math.sqrt(bunsan));
            }
        }   
    }
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[]args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
            int sum=0;
            double sqsum=0;
            int n=sc.nextInt();
            if(n==0) break;
            int[] score = new int[n];
            for(int i=0;i<score.length;i++){
                score[i]=sc.nextInt();
                sum+=score[i];
                }
                double ave=0,bunsan=0;
                ave=(double) sum/n;
                for(int i=0;i<score.length;i++){
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                }
                bunsan=(double) sqsum/n;
                System.out.println(Math.sqrt(bunsan));
            }
        }   
    }
} Main public static void main(String[]args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
            int sum=0;
            double sqsum=0;
            int n=sc.nextInt();
            if(n==0) break;
            int[] score = new int[n];
            for(int i=0;i<score.length;i++){
                score[i]=sc.nextInt();
                sum+=score[i];
                }
                double ave=0,bunsan=0;
                ave=(double) sum/n;
                for(int i=0;i<score.length;i++){
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                }
                bunsan=(double) sqsum/n;
                System.out.println(Math.sqrt(bunsan));
            }
        }   
    } main {
        try(Scanner sc = new Scanner(System.in)){
            while(true){
            int sum=0;
            double sqsum=0;
            int n=sc.nextInt();
            if(n==0) break;
            int[] score = new int[n];
            for(int i=0;i<score.length;i++){
                score[i]=sc.nextInt();
                sum+=score[i];
                }
                double ave=0,bunsan=0;
                ave=(double) sum/n;
                for(int i=0;i<score.length;i++){
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                }
                bunsan=(double) sqsum/n;
                System.out.println(Math.sqrt(bunsan));
            }
        }   
    } try(Scanner sc = new Scanner(System.in)){
            while(true){
            int sum=0;
            double sqsum=0;
            int n=sc.nextInt();
            if(n==0) break;
            int[] score = new int[n];
            for(int i=0;i<score.length;i++){
                score[i]=sc.nextInt();
                sum+=score[i];
                }
                double ave=0,bunsan=0;
                ave=(double) sum/n;
                for(int i=0;i<score.length;i++){
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                }
                bunsan=(double) sqsum/n;
                System.out.println(Math.sqrt(bunsan));
            }
        } {
            while(true){
            int sum=0;
            double sqsum=0;
            int n=sc.nextInt();
            if(n==0) break;
            int[] score = new int[n];
            for(int i=0;i<score.length;i++){
                score[i]=sc.nextInt();
                sum+=score[i];
                }
                double ave=0,bunsan=0;
                ave=(double) sum/n;
                for(int i=0;i<score.length;i++){
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                }
                bunsan=(double) sqsum/n;
                System.out.println(Math.sqrt(bunsan));
            }
        } Scanner sc = new Scanner(System.in) Scanner sc = new Scanner(System.in) new Scanner(System.in) while(true){
            int sum=0;
            double sqsum=0;
            int n=sc.nextInt();
            if(n==0) break;
            int[] score = new int[n];
            for(int i=0;i<score.length;i++){
                score[i]=sc.nextInt();
                sum+=score[i];
                }
                double ave=0,bunsan=0;
                ave=(double) sum/n;
                for(int i=0;i<score.length;i++){
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                }
                bunsan=(double) sqsum/n;
                System.out.println(Math.sqrt(bunsan));
            } true {
            int sum=0;
            double sqsum=0;
            int n=sc.nextInt();
            if(n==0) break;
            int[] score = new int[n];
            for(int i=0;i<score.length;i++){
                score[i]=sc.nextInt();
                sum+=score[i];
                }
                double ave=0,bunsan=0;
                ave=(double) sum/n;
                for(int i=0;i<score.length;i++){
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                }
                bunsan=(double) sqsum/n;
                System.out.println(Math.sqrt(bunsan));
            } int sum=0; sum 0 double sqsum=0; sqsum 0 int n=sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n==0) break; n==0 n 0 break; int[] score = new int[n]; score new int[n] n for(int i=0;i<score.length;i++){
                score[i]=sc.nextInt();
                sum+=score[i];
                } int i=0; int i=0; i 0 i<score.length i score.length score score.length i++ i++ i {
                score[i]=sc.nextInt();
                sum+=score[i];
                } {
                score[i]=sc.nextInt();
                sum+=score[i];
                } score[i]=sc.nextInt() score[i] score i sc.nextInt() sc.nextInt sc sum+=score[i] sum score[i] score i double ave=0 ave 0 bunsan=0; bunsan 0 ave=(double) sum/n ave (double) sum/n (double) sum n for(int i=0;i<score.length;i++){
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                } int i=0; int i=0; i 0 i<score.length i score.length score score.length i++ i++ i {
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                } {
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                } sqsum+=(score[i]-ave)*(score[i]-ave) sqsum (score[i]-ave)*(score[i]-ave) (score[i]-ave) score[i] score i ave (score[i]-ave) score[i] score i ave bunsan=(double) sqsum/n bunsan (double) sqsum/n (double) sqsum n System.out.println(Math.sqrt(bunsan)) System.out.println System.out System System.out Math.sqrt(bunsan) Math.sqrt Math bunsan String[]args args public class Main{
    public static void main(String[]args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
            int sum=0;
            double sqsum=0;
            int n=sc.nextInt();
            if(n==0) break;
            int[] score = new int[n];
            for(int i=0;i<score.length;i++){
                score[i]=sc.nextInt();
                sum+=score[i];
                }
                double ave=0,bunsan=0;
                ave=(double) sum/n;
                for(int i=0;i<score.length;i++){
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                }
                bunsan=(double) sqsum/n;
                System.out.println(Math.sqrt(bunsan));
            }
        }   
    }
} public class Main{
    public static void main(String[]args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
            int sum=0;
            double sqsum=0;
            int n=sc.nextInt();
            if(n==0) break;
            int[] score = new int[n];
            for(int i=0;i<score.length;i++){
                score[i]=sc.nextInt();
                sum+=score[i];
                }
                double ave=0,bunsan=0;
                ave=(double) sum/n;
                for(int i=0;i<score.length;i++){
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                }
                bunsan=(double) sqsum/n;
                System.out.println(Math.sqrt(bunsan));
            }
        }   
    }
} Main
import java.util.Scanner;

public class Main{
    public static void main(String[]args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
            int sum=0;
            double sqsum=0;
            int n=sc.nextInt();
            if(n==0) break;
            int[] score = new int[n];
            for(int i=0;i<score.length;i++){
                score[i]=sc.nextInt();
                sum+=score[i];
                }
                double ave=0,bunsan=0;
                ave=(double) sum/n;
                for(int i=0;i<score.length;i++){
                    sqsum+=(score[i]-ave)*(score[i]-ave);
                }
                bunsan=(double) sqsum/n;
                System.out.println(Math.sqrt(bunsan));
            }
        }   
    }
}
