import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        int i;
        double dis,sta;
        Scanner sc=new Scanner(System.in);

        while(true){
            int n=sc.nextInt();
            if(n==0){
                break;
            }
            int sum=0,sqsum=0;
            for(i=0;i<n;i++){
                int score=sc.nextInt();
                sum+=score;
                sqsum+=score*score;
            }
            dis=(double)sqsum/n-(double)sum/n*(double)sum/n;
            sta=Math.sqrt(dis);
            System.out.printf("%.8f\n",sta);
        }
        sc.close();
    }
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args){
        int i;
        double dis,sta;
        Scanner sc=new Scanner(System.in);

        while(true){
            int n=sc.nextInt();
            if(n==0){
                break;
            }
            int sum=0,sqsum=0;
            for(i=0;i<n;i++){
                int score=sc.nextInt();
                sum+=score;
                sqsum+=score*score;
            }
            dis=(double)sqsum/n-(double)sum/n*(double)sum/n;
            sta=Math.sqrt(dis);
            System.out.printf("%.8f\n",sta);
        }
        sc.close();
    }
} Main public static void main(String[] args){
        int i;
        double dis,sta;
        Scanner sc=new Scanner(System.in);

        while(true){
            int n=sc.nextInt();
            if(n==0){
                break;
            }
            int sum=0,sqsum=0;
            for(i=0;i<n;i++){
                int score=sc.nextInt();
                sum+=score;
                sqsum+=score*score;
            }
            dis=(double)sqsum/n-(double)sum/n*(double)sum/n;
            sta=Math.sqrt(dis);
            System.out.printf("%.8f\n",sta);
        }
        sc.close();
    } main {
        int i;
        double dis,sta;
        Scanner sc=new Scanner(System.in);

        while(true){
            int n=sc.nextInt();
            if(n==0){
                break;
            }
            int sum=0,sqsum=0;
            for(i=0;i<n;i++){
                int score=sc.nextInt();
                sum+=score;
                sqsum+=score*score;
            }
            dis=(double)sqsum/n-(double)sum/n*(double)sum/n;
            sta=Math.sqrt(dis);
            System.out.printf("%.8f\n",sta);
        }
        sc.close();
    } int i; i double dis dis sta; sta Scanner sc=new Scanner(System.in); sc new Scanner(System.in) while(true){
            int n=sc.nextInt();
            if(n==0){
                break;
            }
            int sum=0,sqsum=0;
            for(i=0;i<n;i++){
                int score=sc.nextInt();
                sum+=score;
                sqsum+=score*score;
            }
            dis=(double)sqsum/n-(double)sum/n*(double)sum/n;
            sta=Math.sqrt(dis);
            System.out.printf("%.8f\n",sta);
        } true {
            int n=sc.nextInt();
            if(n==0){
                break;
            }
            int sum=0,sqsum=0;
            for(i=0;i<n;i++){
                int score=sc.nextInt();
                sum+=score;
                sqsum+=score*score;
            }
            dis=(double)sqsum/n-(double)sum/n*(double)sum/n;
            sta=Math.sqrt(dis);
            System.out.printf("%.8f\n",sta);
        } int n=sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n==0){
                break;
            } n==0 n 0 {
                break;
            } break; int sum=0 sum 0 sqsum=0; sqsum 0 for(i=0;i<n;i++){
                int score=sc.nextInt();
                sum+=score;
                sqsum+=score*score;
            } i=0; i=0 i 0 i<n i n i++ i++ i {
                int score=sc.nextInt();
                sum+=score;
                sqsum+=score*score;
            } {
                int score=sc.nextInt();
                sum+=score;
                sqsum+=score*score;
            } int score=sc.nextInt(); score sc.nextInt() sc.nextInt sc sum+=score sum score sqsum+=score*score sqsum score*score score score dis=(double)sqsum/n-(double)sum/n*(double)sum/n dis (double)sqsum/n-(double)sum/n*(double)sum/n (double)sqsum/n (double)sqsum n (double)sum/n*(double)sum/n (double)sum/n*(double)sum (double)sum/n (double)sum n (double)sum n sta=Math.sqrt(dis) sta Math.sqrt(dis) Math.sqrt Math dis System.out.printf("%.8f\n",sta) System.out.printf System.out System System.out "%.8f\n" sta sc.close() sc.close sc String[] args args public class Main{
    public static void main(String[] args){
        int i;
        double dis,sta;
        Scanner sc=new Scanner(System.in);

        while(true){
            int n=sc.nextInt();
            if(n==0){
                break;
            }
            int sum=0,sqsum=0;
            for(i=0;i<n;i++){
                int score=sc.nextInt();
                sum+=score;
                sqsum+=score*score;
            }
            dis=(double)sqsum/n-(double)sum/n*(double)sum/n;
            sta=Math.sqrt(dis);
            System.out.printf("%.8f\n",sta);
        }
        sc.close();
    }
} public class Main{
    public static void main(String[] args){
        int i;
        double dis,sta;
        Scanner sc=new Scanner(System.in);

        while(true){
            int n=sc.nextInt();
            if(n==0){
                break;
            }
            int sum=0,sqsum=0;
            for(i=0;i<n;i++){
                int score=sc.nextInt();
                sum+=score;
                sqsum+=score*score;
            }
            dis=(double)sqsum/n-(double)sum/n*(double)sum/n;
            sta=Math.sqrt(dis);
            System.out.printf("%.8f\n",sta);
        }
        sc.close();
    }
} Main
import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        int i;
        double dis,sta;
        Scanner sc=new Scanner(System.in);

        while(true){
            int n=sc.nextInt();
            if(n==0){
                break;
            }
            int sum=0,sqsum=0;
            for(i=0;i<n;i++){
                int score=sc.nextInt();
                sum+=score;
                sqsum+=score*score;
            }
            dis=(double)sqsum/n-(double)sum/n*(double)sum/n;
            sta=Math.sqrt(dis);
            System.out.printf("%.8f\n",sta);
        }
        sc.close();
    }
}
