import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        
        int n,i,sum1=0;
        int[] score;
        double ave,div,sum2=0;

        score = new int[1000];

        while(true){
            n=scan.nextInt();
            if(n==0){
                break;
            }

            for(i=0;i<n;i++){
                score[i]=scan.nextInt();
                sum1+=score[i];
            }

            ave=(double)sum1/n;
            
            for(i=0;i<n;i++){
                sum2+=((score[i]-ave)*(score[i]-ave));
            }
            div=(double)sum2/n;

            System.out.println(Math.sqrt(div));

            sum1=0;
            sum2=0;
        }

    }
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        
        int n,i,sum1=0;
        int[] score;
        double ave,div,sum2=0;

        score = new int[1000];

        while(true){
            n=scan.nextInt();
            if(n==0){
                break;
            }

            for(i=0;i<n;i++){
                score[i]=scan.nextInt();
                sum1+=score[i];
            }

            ave=(double)sum1/n;
            
            for(i=0;i<n;i++){
                sum2+=((score[i]-ave)*(score[i]-ave));
            }
            div=(double)sum2/n;

            System.out.println(Math.sqrt(div));

            sum1=0;
            sum2=0;
        }

    }
} Main public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        
        int n,i,sum1=0;
        int[] score;
        double ave,div,sum2=0;

        score = new int[1000];

        while(true){
            n=scan.nextInt();
            if(n==0){
                break;
            }

            for(i=0;i<n;i++){
                score[i]=scan.nextInt();
                sum1+=score[i];
            }

            ave=(double)sum1/n;
            
            for(i=0;i<n;i++){
                sum2+=((score[i]-ave)*(score[i]-ave));
            }
            div=(double)sum2/n;

            System.out.println(Math.sqrt(div));

            sum1=0;
            sum2=0;
        }

    } main {
        Scanner scan = new Scanner(System.in);
        
        int n,i,sum1=0;
        int[] score;
        double ave,div,sum2=0;

        score = new int[1000];

        while(true){
            n=scan.nextInt();
            if(n==0){
                break;
            }

            for(i=0;i<n;i++){
                score[i]=scan.nextInt();
                sum1+=score[i];
            }

            ave=(double)sum1/n;
            
            for(i=0;i<n;i++){
                sum2+=((score[i]-ave)*(score[i]-ave));
            }
            div=(double)sum2/n;

            System.out.println(Math.sqrt(div));

            sum1=0;
            sum2=0;
        }

    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int n n i i sum1=0; sum1 0 int[] score; score double ave ave div div sum2=0; sum2 0 score = new int[1000] score new int[1000] 1000 while(true){
            n=scan.nextInt();
            if(n==0){
                break;
            }

            for(i=0;i<n;i++){
                score[i]=scan.nextInt();
                sum1+=score[i];
            }

            ave=(double)sum1/n;
            
            for(i=0;i<n;i++){
                sum2+=((score[i]-ave)*(score[i]-ave));
            }
            div=(double)sum2/n;

            System.out.println(Math.sqrt(div));

            sum1=0;
            sum2=0;
        } true {
            n=scan.nextInt();
            if(n==0){
                break;
            }

            for(i=0;i<n;i++){
                score[i]=scan.nextInt();
                sum1+=score[i];
            }

            ave=(double)sum1/n;
            
            for(i=0;i<n;i++){
                sum2+=((score[i]-ave)*(score[i]-ave));
            }
            div=(double)sum2/n;

            System.out.println(Math.sqrt(div));

            sum1=0;
            sum2=0;
        } n=scan.nextInt() n scan.nextInt() scan.nextInt scan if(n==0){
                break;
            } n==0 n 0 {
                break;
            } break; for(i=0;i<n;i++){
                score[i]=scan.nextInt();
                sum1+=score[i];
            } i=0; i=0 i 0 i<n i n i++ i++ i {
                score[i]=scan.nextInt();
                sum1+=score[i];
            } {
                score[i]=scan.nextInt();
                sum1+=score[i];
            } score[i]=scan.nextInt() score[i] score i scan.nextInt() scan.nextInt scan sum1+=score[i] sum1 score[i] score i ave=(double)sum1/n ave (double)sum1/n (double)sum1 n for(i=0;i<n;i++){
                sum2+=((score[i]-ave)*(score[i]-ave));
            } i=0; i=0 i 0 i<n i n i++ i++ i {
                sum2+=((score[i]-ave)*(score[i]-ave));
            } {
                sum2+=((score[i]-ave)*(score[i]-ave));
            } sum2+=((score[i]-ave)*(score[i]-ave)) sum2 ((score[i]-ave)*(score[i]-ave)) (score[i]-ave) score[i] score i ave (score[i]-ave) score[i] score i ave div=(double)sum2/n div (double)sum2/n (double)sum2 n System.out.println(Math.sqrt(div)) System.out.println System.out System System.out Math.sqrt(div) Math.sqrt Math div sum1=0 sum1 0 sum2=0 sum2 0 String[] args args public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        
        int n,i,sum1=0;
        int[] score;
        double ave,div,sum2=0;

        score = new int[1000];

        while(true){
            n=scan.nextInt();
            if(n==0){
                break;
            }

            for(i=0;i<n;i++){
                score[i]=scan.nextInt();
                sum1+=score[i];
            }

            ave=(double)sum1/n;
            
            for(i=0;i<n;i++){
                sum2+=((score[i]-ave)*(score[i]-ave));
            }
            div=(double)sum2/n;

            System.out.println(Math.sqrt(div));

            sum1=0;
            sum2=0;
        }

    }
} public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        
        int n,i,sum1=0;
        int[] score;
        double ave,div,sum2=0;

        score = new int[1000];

        while(true){
            n=scan.nextInt();
            if(n==0){
                break;
            }

            for(i=0;i<n;i++){
                score[i]=scan.nextInt();
                sum1+=score[i];
            }

            ave=(double)sum1/n;
            
            for(i=0;i<n;i++){
                sum2+=((score[i]-ave)*(score[i]-ave));
            }
            div=(double)sum2/n;

            System.out.println(Math.sqrt(div));

            sum1=0;
            sum2=0;
        }

    }
} Main
import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        
        int n,i,sum1=0;
        int[] score;
        double ave,div,sum2=0;

        score = new int[1000];

        while(true){
            n=scan.nextInt();
            if(n==0){
                break;
            }

            for(i=0;i<n;i++){
                score[i]=scan.nextInt();
                sum1+=score[i];
            }

            ave=(double)sum1/n;
            
            for(i=0;i<n;i++){
                sum2+=((score[i]-ave)*(score[i]-ave));
            }
            div=(double)sum2/n;

            System.out.println(Math.sqrt(div));

            sum1=0;
            sum2=0;
        }

    }
}
