import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                int a=0;
                if(n==0){ break; }
                int[] scores = new int[n];
                for(int i=0; i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    a=a+scores[i];
                }
                double average = 0.0;
                double variance = 0.0;
                average = (double)a/n;
                for(int i=0;i<scores.length;i++) {
                    variance = variance + (scores[i] - average) * (scores[i] - average);
                }
                variance=variance/n;
                System.out.println(Math.sqrt(variance));
            }
        }
    }
}
 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 n = sc.nextInt();
                int a=0;
                if(n==0){ break; }
                int[] scores = new int[n];
                for(int i=0; i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    a=a+scores[i];
                }
                double average = 0.0;
                double variance = 0.0;
                average = (double)a/n;
                for(int i=0;i<scores.length;i++) {
                    variance = variance + (scores[i] - average) * (scores[i] - average);
                }
                variance=variance/n;
                System.out.println(Math.sqrt(variance));
            }
        }
    }
} Main public static void main(String[] args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                int a=0;
                if(n==0){ break; }
                int[] scores = new int[n];
                for(int i=0; i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    a=a+scores[i];
                }
                double average = 0.0;
                double variance = 0.0;
                average = (double)a/n;
                for(int i=0;i<scores.length;i++) {
                    variance = variance + (scores[i] - average) * (scores[i] - average);
                }
                variance=variance/n;
                System.out.println(Math.sqrt(variance));
            }
        }
    } main {
        try(Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                int a=0;
                if(n==0){ break; }
                int[] scores = new int[n];
                for(int i=0; i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    a=a+scores[i];
                }
                double average = 0.0;
                double variance = 0.0;
                average = (double)a/n;
                for(int i=0;i<scores.length;i++) {
                    variance = variance + (scores[i] - average) * (scores[i] - average);
                }
                variance=variance/n;
                System.out.println(Math.sqrt(variance));
            }
        }
    } try(Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                int a=0;
                if(n==0){ break; }
                int[] scores = new int[n];
                for(int i=0; i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    a=a+scores[i];
                }
                double average = 0.0;
                double variance = 0.0;
                average = (double)a/n;
                for(int i=0;i<scores.length;i++) {
                    variance = variance + (scores[i] - average) * (scores[i] - average);
                }
                variance=variance/n;
                System.out.println(Math.sqrt(variance));
            }
        } {
            while(true){
                int n = sc.nextInt();
                int a=0;
                if(n==0){ break; }
                int[] scores = new int[n];
                for(int i=0; i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    a=a+scores[i];
                }
                double average = 0.0;
                double variance = 0.0;
                average = (double)a/n;
                for(int i=0;i<scores.length;i++) {
                    variance = variance + (scores[i] - average) * (scores[i] - average);
                }
                variance=variance/n;
                System.out.println(Math.sqrt(variance));
            }
        } Scanner sc = new Scanner(System.in) Scanner sc = new Scanner(System.in) new Scanner(System.in) while(true){
                int n = sc.nextInt();
                int a=0;
                if(n==0){ break; }
                int[] scores = new int[n];
                for(int i=0; i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    a=a+scores[i];
                }
                double average = 0.0;
                double variance = 0.0;
                average = (double)a/n;
                for(int i=0;i<scores.length;i++) {
                    variance = variance + (scores[i] - average) * (scores[i] - average);
                }
                variance=variance/n;
                System.out.println(Math.sqrt(variance));
            } true {
                int n = sc.nextInt();
                int a=0;
                if(n==0){ break; }
                int[] scores = new int[n];
                for(int i=0; i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    a=a+scores[i];
                }
                double average = 0.0;
                double variance = 0.0;
                average = (double)a/n;
                for(int i=0;i<scores.length;i++) {
                    variance = variance + (scores[i] - average) * (scores[i] - average);
                }
                variance=variance/n;
                System.out.println(Math.sqrt(variance));
            } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int a=0; a 0 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();
                    a=a+scores[i];
                } int i=0; int i=0; i 0 i<scores.length i scores.length scores scores.length i++ i++ i {
                    scores[i] = sc.nextInt();
                    a=a+scores[i];
                } {
                    scores[i] = sc.nextInt();
                    a=a+scores[i];
                } scores[i] = sc.nextInt() scores[i] scores i sc.nextInt() sc.nextInt sc a=a+scores[i] a a+scores[i] a scores[i] scores i double average = 0.0; average 0.0 double variance = 0.0; variance 0.0 average = (double)a/n average (double)a/n (double)a n for(int i=0;i<scores.length;i++) {
                    variance = variance + (scores[i] - average) * (scores[i] - average);
                } int i=0; int i=0; i 0 i<scores.length i scores.length scores scores.length i++ i++ i {
                    variance = variance + (scores[i] - average) * (scores[i] - average);
                } {
                    variance = variance + (scores[i] - average) * (scores[i] - average);
                } variance = variance + (scores[i] - average) * (scores[i] - average) variance variance + (scores[i] - average) * (scores[i] - average) variance (scores[i] - average) * (scores[i] - average) (scores[i] - average) scores[i] scores i average (scores[i] - average) scores[i] scores i average variance=variance/n variance variance/n variance n System.out.println(Math.sqrt(variance)) System.out.println System.out System System.out Math.sqrt(variance) Math.sqrt Math variance String[] args args public class Main {
    public static void main(String[] args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                int a=0;
                if(n==0){ break; }
                int[] scores = new int[n];
                for(int i=0; i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    a=a+scores[i];
                }
                double average = 0.0;
                double variance = 0.0;
                average = (double)a/n;
                for(int i=0;i<scores.length;i++) {
                    variance = variance + (scores[i] - average) * (scores[i] - average);
                }
                variance=variance/n;
                System.out.println(Math.sqrt(variance));
            }
        }
    }
} public class Main {
    public static void main(String[] args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                int a=0;
                if(n==0){ break; }
                int[] scores = new int[n];
                for(int i=0; i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    a=a+scores[i];
                }
                double average = 0.0;
                double variance = 0.0;
                average = (double)a/n;
                for(int i=0;i<scores.length;i++) {
                    variance = variance + (scores[i] - average) * (scores[i] - average);
                }
                variance=variance/n;
                System.out.println(Math.sqrt(variance));
            }
        }
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                int a=0;
                if(n==0){ break; }
                int[] scores = new int[n];
                for(int i=0; i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    a=a+scores[i];
                }
                double average = 0.0;
                double variance = 0.0;
                average = (double)a/n;
                for(int i=0;i<scores.length;i++) {
                    variance = variance + (scores[i] - average) * (scores[i] - average);
                }
                variance=variance/n;
                System.out.println(Math.sqrt(variance));
            }
        }
    }
}

