import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        try (java.util.Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                if(n==0){break;}
                int[] scores = new int[n];
                for(int i=0; i < scores.length; i ++){
                    scores[i] = sc.nextInt();
                }
                double average = 0, variance = 0;
                int sum = 0;
                for(int i=0; i < scores.length; i ++){
                    sum += scores[i];
                }
                average = (double)sum / n;
                double var = 0;
                for(int i=0; i<scores.length; i ++){
                    var += Math.pow(scores[i] - average, 2);
                }
                variance = var/n;
                System.out.println(String.format("%.8f",Math.sqrt(variance)));
            }
            sc.close();
        } 
    }
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args){
        try (java.util.Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                if(n==0){break;}
                int[] scores = new int[n];
                for(int i=0; i < scores.length; i ++){
                    scores[i] = sc.nextInt();
                }
                double average = 0, variance = 0;
                int sum = 0;
                for(int i=0; i < scores.length; i ++){
                    sum += scores[i];
                }
                average = (double)sum / n;
                double var = 0;
                for(int i=0; i<scores.length; i ++){
                    var += Math.pow(scores[i] - average, 2);
                }
                variance = var/n;
                System.out.println(String.format("%.8f",Math.sqrt(variance)));
            }
            sc.close();
        } 
    }
} Main public static void main(String[] args){
        try (java.util.Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                if(n==0){break;}
                int[] scores = new int[n];
                for(int i=0; i < scores.length; i ++){
                    scores[i] = sc.nextInt();
                }
                double average = 0, variance = 0;
                int sum = 0;
                for(int i=0; i < scores.length; i ++){
                    sum += scores[i];
                }
                average = (double)sum / n;
                double var = 0;
                for(int i=0; i<scores.length; i ++){
                    var += Math.pow(scores[i] - average, 2);
                }
                variance = var/n;
                System.out.println(String.format("%.8f",Math.sqrt(variance)));
            }
            sc.close();
        } 
    } main {
        try (java.util.Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                if(n==0){break;}
                int[] scores = new int[n];
                for(int i=0; i < scores.length; i ++){
                    scores[i] = sc.nextInt();
                }
                double average = 0, variance = 0;
                int sum = 0;
                for(int i=0; i < scores.length; i ++){
                    sum += scores[i];
                }
                average = (double)sum / n;
                double var = 0;
                for(int i=0; i<scores.length; i ++){
                    var += Math.pow(scores[i] - average, 2);
                }
                variance = var/n;
                System.out.println(String.format("%.8f",Math.sqrt(variance)));
            }
            sc.close();
        } 
    } try (java.util.Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                if(n==0){break;}
                int[] scores = new int[n];
                for(int i=0; i < scores.length; i ++){
                    scores[i] = sc.nextInt();
                }
                double average = 0, variance = 0;
                int sum = 0;
                for(int i=0; i < scores.length; i ++){
                    sum += scores[i];
                }
                average = (double)sum / n;
                double var = 0;
                for(int i=0; i<scores.length; i ++){
                    var += Math.pow(scores[i] - average, 2);
                }
                variance = var/n;
                System.out.println(String.format("%.8f",Math.sqrt(variance)));
            }
            sc.close();
        } {
            while(true){
                int n = sc.nextInt();
                if(n==0){break;}
                int[] scores = new int[n];
                for(int i=0; i < scores.length; i ++){
                    scores[i] = sc.nextInt();
                }
                double average = 0, variance = 0;
                int sum = 0;
                for(int i=0; i < scores.length; i ++){
                    sum += scores[i];
                }
                average = (double)sum / n;
                double var = 0;
                for(int i=0; i<scores.length; i ++){
                    var += Math.pow(scores[i] - average, 2);
                }
                variance = var/n;
                System.out.println(String.format("%.8f",Math.sqrt(variance)));
            }
            sc.close();
        } java.util.Scanner sc = new Scanner(System.in) java.util.Scanner sc = new Scanner(System.in) new Scanner(System.in) while(true){
                int n = sc.nextInt();
                if(n==0){break;}
                int[] scores = new int[n];
                for(int i=0; i < scores.length; i ++){
                    scores[i] = sc.nextInt();
                }
                double average = 0, variance = 0;
                int sum = 0;
                for(int i=0; i < scores.length; i ++){
                    sum += scores[i];
                }
                average = (double)sum / n;
                double var = 0;
                for(int i=0; i<scores.length; i ++){
                    var += Math.pow(scores[i] - average, 2);
                }
                variance = var/n;
                System.out.println(String.format("%.8f",Math.sqrt(variance)));
            } true {
                int n = sc.nextInt();
                if(n==0){break;}
                int[] scores = new int[n];
                for(int i=0; i < scores.length; i ++){
                    scores[i] = sc.nextInt();
                }
                double average = 0, variance = 0;
                int sum = 0;
                for(int i=0; i < scores.length; i ++){
                    sum += scores[i];
                }
                average = (double)sum / n;
                double var = 0;
                for(int i=0; i<scores.length; i ++){
                    var += Math.pow(scores[i] - average, 2);
                }
                variance = var/n;
                System.out.println(String.format("%.8f",Math.sqrt(variance)));
            } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc 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 < scores.length; i ++){
                    scores[i] = sc.nextInt();
                } int i=0; int i=0; i 0 i < scores.length i scores.length scores scores.length i ++ i ++ i {
                    scores[i] = sc.nextInt();
                } {
                    scores[i] = sc.nextInt();
                } scores[i] = sc.nextInt() scores[i] scores i sc.nextInt() sc.nextInt sc double average = 0 average 0 variance = 0; variance 0 int sum = 0; sum 0 for(int i=0; i < scores.length; i ++){
                    sum += scores[i];
                } int i=0; int i=0; i 0 i < scores.length i scores.length scores scores.length i ++ i ++ i {
                    sum += scores[i];
                } {
                    sum += scores[i];
                } sum += scores[i] sum scores[i] scores i average = (double)sum / n average (double)sum / n (double)sum n double var = 0; var 0 for(int i=0; i<scores.length; i ++){
                    var += 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 {
                    var += Math.pow(scores[i] - average, 2);
                } {
                    var += Math.pow(scores[i] - average, 2);
                } var += Math.pow(scores[i] - average, 2) var Math.pow(scores[i] - average, 2) Math.pow Math scores[i] - average scores[i] scores i average 2 variance = var/n variance var/n var n System.out.println(String.format("%.8f",Math.sqrt(variance))) System.out.println System.out System System.out String.format("%.8f",Math.sqrt(variance)) String.format String "%.8f" Math.sqrt(variance) Math.sqrt Math variance sc.close() sc.close sc String[] args args public class Main{
    public static void main(String[] args){
        try (java.util.Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                if(n==0){break;}
                int[] scores = new int[n];
                for(int i=0; i < scores.length; i ++){
                    scores[i] = sc.nextInt();
                }
                double average = 0, variance = 0;
                int sum = 0;
                for(int i=0; i < scores.length; i ++){
                    sum += scores[i];
                }
                average = (double)sum / n;
                double var = 0;
                for(int i=0; i<scores.length; i ++){
                    var += Math.pow(scores[i] - average, 2);
                }
                variance = var/n;
                System.out.println(String.format("%.8f",Math.sqrt(variance)));
            }
            sc.close();
        } 
    }
} public class Main{
    public static void main(String[] args){
        try (java.util.Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                if(n==0){break;}
                int[] scores = new int[n];
                for(int i=0; i < scores.length; i ++){
                    scores[i] = sc.nextInt();
                }
                double average = 0, variance = 0;
                int sum = 0;
                for(int i=0; i < scores.length; i ++){
                    sum += scores[i];
                }
                average = (double)sum / n;
                double var = 0;
                for(int i=0; i<scores.length; i ++){
                    var += Math.pow(scores[i] - average, 2);
                }
                variance = var/n;
                System.out.println(String.format("%.8f",Math.sqrt(variance)));
            }
            sc.close();
        } 
    }
} Main
import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        try (java.util.Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                if(n==0){break;}
                int[] scores = new int[n];
                for(int i=0; i < scores.length; i ++){
                    scores[i] = sc.nextInt();
                }
                double average = 0, variance = 0;
                int sum = 0;
                for(int i=0; i < scores.length; i ++){
                    sum += scores[i];
                }
                average = (double)sum / n;
                double var = 0;
                for(int i=0; i<scores.length; i ++){
                    var += Math.pow(scores[i] - average, 2);
                }
                variance = var/n;
                System.out.println(String.format("%.8f",Math.sqrt(variance)));
            }
            sc.close();
        } 
    }
}
