import java.util.Scanner;
public class Main {
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        while(true){
            int n = scan.nextInt();
            if(n==0){
                break;
            }
            int scores[] = new int[n];
            for(int i=0;i<n;i++){
                scores[i]=scan.nextInt();
            }
            double average=0;
            double variance=0;
            double sum=0;
            for(int i=0;i<scores.length;i++){
                sum = sum + scores[i];
            }
            average = sum/n;
            double sumsum=0;
            for(int i=0;i<scores.length;i++){
                sumsum = sumsum + Math.pow(scores[i] - average,2);
            }
            variance = sumsum/n;
            System.out.println(Math.sqrt(variance));
        }
        scan.close();
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        while(true){
            int n = scan.nextInt();
            if(n==0){
                break;
            }
            int scores[] = new int[n];
            for(int i=0;i<n;i++){
                scores[i]=scan.nextInt();
            }
            double average=0;
            double variance=0;
            double sum=0;
            for(int i=0;i<scores.length;i++){
                sum = sum + scores[i];
            }
            average = sum/n;
            double sumsum=0;
            for(int i=0;i<scores.length;i++){
                sumsum = sumsum + Math.pow(scores[i] - average,2);
            }
            variance = sumsum/n;
            System.out.println(Math.sqrt(variance));
        }
        scan.close();
    }
} Main public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        while(true){
            int n = scan.nextInt();
            if(n==0){
                break;
            }
            int scores[] = new int[n];
            for(int i=0;i<n;i++){
                scores[i]=scan.nextInt();
            }
            double average=0;
            double variance=0;
            double sum=0;
            for(int i=0;i<scores.length;i++){
                sum = sum + scores[i];
            }
            average = sum/n;
            double sumsum=0;
            for(int i=0;i<scores.length;i++){
                sumsum = sumsum + Math.pow(scores[i] - average,2);
            }
            variance = sumsum/n;
            System.out.println(Math.sqrt(variance));
        }
        scan.close();
    } main {
        Scanner scan = new Scanner(System.in);
        while(true){
            int n = scan.nextInt();
            if(n==0){
                break;
            }
            int scores[] = new int[n];
            for(int i=0;i<n;i++){
                scores[i]=scan.nextInt();
            }
            double average=0;
            double variance=0;
            double sum=0;
            for(int i=0;i<scores.length;i++){
                sum = sum + scores[i];
            }
            average = sum/n;
            double sumsum=0;
            for(int i=0;i<scores.length;i++){
                sumsum = sumsum + Math.pow(scores[i] - average,2);
            }
            variance = sumsum/n;
            System.out.println(Math.sqrt(variance));
        }
        scan.close();
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) while(true){
            int n = scan.nextInt();
            if(n==0){
                break;
            }
            int scores[] = new int[n];
            for(int i=0;i<n;i++){
                scores[i]=scan.nextInt();
            }
            double average=0;
            double variance=0;
            double sum=0;
            for(int i=0;i<scores.length;i++){
                sum = sum + scores[i];
            }
            average = sum/n;
            double sumsum=0;
            for(int i=0;i<scores.length;i++){
                sumsum = sumsum + Math.pow(scores[i] - average,2);
            }
            variance = sumsum/n;
            System.out.println(Math.sqrt(variance));
        } true {
            int n = scan.nextInt();
            if(n==0){
                break;
            }
            int scores[] = new int[n];
            for(int i=0;i<n;i++){
                scores[i]=scan.nextInt();
            }
            double average=0;
            double variance=0;
            double sum=0;
            for(int i=0;i<scores.length;i++){
                sum = sum + scores[i];
            }
            average = sum/n;
            double sumsum=0;
            for(int i=0;i<scores.length;i++){
                sumsum = sumsum + Math.pow(scores[i] - average,2);
            }
            variance = sumsum/n;
            System.out.println(Math.sqrt(variance));
        } int n = scan.nextInt(); n scan.nextInt() scan.nextInt scan if(n==0){
                break;
            } n==0 n 0 {
                break;
            } break; int scores[] = new int[n]; scores new int[n] n for(int i=0;i<n;i++){
                scores[i]=scan.nextInt();
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                scores[i]=scan.nextInt();
            } {
                scores[i]=scan.nextInt();
            } scores[i]=scan.nextInt() scores[i] scores i scan.nextInt() scan.nextInt scan double average=0; average 0 double variance=0; variance 0 double sum=0; sum 0 for(int i=0;i<scores.length;i++){
                sum = sum + scores[i];
            } int i=0; int i=0; i 0 i<scores.length i scores.length scores scores.length i++ i++ i {
                sum = sum + scores[i];
            } {
                sum = sum + scores[i];
            } sum = sum + scores[i] sum sum + scores[i] sum scores[i] scores i average = sum/n average sum/n sum n double sumsum=0; sumsum 0 for(int i=0;i<scores.length;i++){
                sumsum = sumsum + Math.pow(scores[i] - average,2);
            } int i=0; int i=0; i 0 i<scores.length i scores.length scores scores.length i++ i++ i {
                sumsum = sumsum + Math.pow(scores[i] - average,2);
            } {
                sumsum = sumsum + Math.pow(scores[i] - average,2);
            } sumsum = sumsum + Math.pow(scores[i] - average,2) sumsum sumsum + Math.pow(scores[i] - average,2) sumsum Math.pow(scores[i] - average,2) Math.pow Math scores[i] - average scores[i] scores i average 2 variance = sumsum/n variance sumsum/n sumsum n System.out.println(Math.sqrt(variance)) System.out.println System.out System System.out Math.sqrt(variance) Math.sqrt Math variance scan.close() scan.close scan String[] args args public class Main {
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        while(true){
            int n = scan.nextInt();
            if(n==0){
                break;
            }
            int scores[] = new int[n];
            for(int i=0;i<n;i++){
                scores[i]=scan.nextInt();
            }
            double average=0;
            double variance=0;
            double sum=0;
            for(int i=0;i<scores.length;i++){
                sum = sum + scores[i];
            }
            average = sum/n;
            double sumsum=0;
            for(int i=0;i<scores.length;i++){
                sumsum = sumsum + Math.pow(scores[i] - average,2);
            }
            variance = sumsum/n;
            System.out.println(Math.sqrt(variance));
        }
        scan.close();
    }
} public class Main {
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        while(true){
            int n = scan.nextInt();
            if(n==0){
                break;
            }
            int scores[] = new int[n];
            for(int i=0;i<n;i++){
                scores[i]=scan.nextInt();
            }
            double average=0;
            double variance=0;
            double sum=0;
            for(int i=0;i<scores.length;i++){
                sum = sum + scores[i];
            }
            average = sum/n;
            double sumsum=0;
            for(int i=0;i<scores.length;i++){
                sumsum = sumsum + Math.pow(scores[i] - average,2);
            }
            variance = sumsum/n;
            System.out.println(Math.sqrt(variance));
        }
        scan.close();
    }
} Main
import java.util.Scanner;
public class Main {
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        while(true){
            int n = scan.nextInt();
            if(n==0){
                break;
            }
            int scores[] = new int[n];
            for(int i=0;i<n;i++){
                scores[i]=scan.nextInt();
            }
            double average=0;
            double variance=0;
            double sum=0;
            for(int i=0;i<scores.length;i++){
                sum = sum + scores[i];
            }
            average = sum/n;
            double sumsum=0;
            for(int i=0;i<scores.length;i++){
                sumsum = sumsum + Math.pow(scores[i] - average,2);
            }
            variance = sumsum/n;
            System.out.println(Math.sqrt(variance));
        }
        scan.close();
    }
}
