import java.util.Scanner;
public class Main {
    public static void main(String[] args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
                double sum = 0, ave, var = 0;
                int n = sc.nextInt();
                if(n==0) break;
                int[] scores = new int[n];
                for(int i=0;i<n;i++) {
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                ave = sum/n;

                for(int i=0; i<n; i++){
                    var += Math.pow((scores[i] - ave),2)/n;
                }

                System.out.printf("%f\n",Math.sqrt(var));
            }
        }
    }
} 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){
                double sum = 0, ave, var = 0;
                int n = sc.nextInt();
                if(n==0) break;
                int[] scores = new int[n];
                for(int i=0;i<n;i++) {
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                ave = sum/n;

                for(int i=0; i<n; i++){
                    var += Math.pow((scores[i] - ave),2)/n;
                }

                System.out.printf("%f\n",Math.sqrt(var));
            }
        }
    }
} Main public static void main(String[] args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
                double sum = 0, ave, var = 0;
                int n = sc.nextInt();
                if(n==0) break;
                int[] scores = new int[n];
                for(int i=0;i<n;i++) {
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                ave = sum/n;

                for(int i=0; i<n; i++){
                    var += Math.pow((scores[i] - ave),2)/n;
                }

                System.out.printf("%f\n",Math.sqrt(var));
            }
        }
    } main {
        try(Scanner sc = new Scanner(System.in)){
            while(true){
                double sum = 0, ave, var = 0;
                int n = sc.nextInt();
                if(n==0) break;
                int[] scores = new int[n];
                for(int i=0;i<n;i++) {
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                ave = sum/n;

                for(int i=0; i<n; i++){
                    var += Math.pow((scores[i] - ave),2)/n;
                }

                System.out.printf("%f\n",Math.sqrt(var));
            }
        }
    } try(Scanner sc = new Scanner(System.in)){
            while(true){
                double sum = 0, ave, var = 0;
                int n = sc.nextInt();
                if(n==0) break;
                int[] scores = new int[n];
                for(int i=0;i<n;i++) {
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                ave = sum/n;

                for(int i=0; i<n; i++){
                    var += Math.pow((scores[i] - ave),2)/n;
                }

                System.out.printf("%f\n",Math.sqrt(var));
            }
        } {
            while(true){
                double sum = 0, ave, var = 0;
                int n = sc.nextInt();
                if(n==0) break;
                int[] scores = new int[n];
                for(int i=0;i<n;i++) {
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                ave = sum/n;

                for(int i=0; i<n; i++){
                    var += Math.pow((scores[i] - ave),2)/n;
                }

                System.out.printf("%f\n",Math.sqrt(var));
            }
        } Scanner sc = new Scanner(System.in) Scanner sc = new Scanner(System.in) new Scanner(System.in) while(true){
                double sum = 0, ave, var = 0;
                int n = sc.nextInt();
                if(n==0) break;
                int[] scores = new int[n];
                for(int i=0;i<n;i++) {
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                ave = sum/n;

                for(int i=0; i<n; i++){
                    var += Math.pow((scores[i] - ave),2)/n;
                }

                System.out.printf("%f\n",Math.sqrt(var));
            } true {
                double sum = 0, ave, var = 0;
                int n = sc.nextInt();
                if(n==0) break;
                int[] scores = new int[n];
                for(int i=0;i<n;i++) {
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                ave = sum/n;

                for(int i=0; i<n; i++){
                    var += Math.pow((scores[i] - ave),2)/n;
                }

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

                for(int i=0; i<n; i++){
                    var += Math.pow((scores[i] - ave),2)/n;
                }

                System.out.printf("%f\n",Math.sqrt(var));
            }
        }
    }
} public class Main {
    public static void main(String[] args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
                double sum = 0, ave, var = 0;
                int n = sc.nextInt();
                if(n==0) break;
                int[] scores = new int[n];
                for(int i=0;i<n;i++) {
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                ave = sum/n;

                for(int i=0; i<n; i++){
                    var += Math.pow((scores[i] - ave),2)/n;
                }

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

                for(int i=0; i<n; i++){
                    var += Math.pow((scores[i] - ave),2)/n;
                }

                System.out.printf("%f\n",Math.sqrt(var));
            }
        }
    }
}
