import java.util.Scanner;

public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            double ave = 0;
            double bun = 0;
            double bunm = 0;
            if(n == 0){
                break;
            }
            int[] ten = new int[n];
            for(int i = 0; i < ten.length;i++){
                ten[i] = sc.nextInt();
            }
            for(int i = 0;i <ten.length; i++){
                ave += ten[i];
            }
            ave = ave/ten.length;

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

            for(int i = 0;i < ten.length;i++){
                bunm = ten[i] - ave;
                bun += bunm*bunm;
            }
            bun = bun/ten.length;
            System.out.println(Math.sqrt(bun));
        }
        sc.close();
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            double ave = 0;
            double bun = 0;
            double bunm = 0;
            if(n == 0){
                break;
            }
            int[] ten = new int[n];
            for(int i = 0; i < ten.length;i++){
                ten[i] = sc.nextInt();
            }
            for(int i = 0;i <ten.length; i++){
                ave += ten[i];
            }
            ave = ave/ten.length;

            for(int i = 0;i < ten.length;i++){
                bunm = ten[i] - ave;
                bun += bunm*bunm;
            }
            bun = bun/ten.length;
            System.out.println(Math.sqrt(bun));
        }
        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            double ave = 0;
            double bun = 0;
            double bunm = 0;
            if(n == 0){
                break;
            }
            int[] ten = new int[n];
            for(int i = 0; i < ten.length;i++){
                ten[i] = sc.nextInt();
            }
            for(int i = 0;i <ten.length; i++){
                ave += ten[i];
            }
            ave = ave/ten.length;

            for(int i = 0;i < ten.length;i++){
                bunm = ten[i] - ave;
                bun += bunm*bunm;
            }
            bun = bun/ten.length;
            System.out.println(Math.sqrt(bun));
        }
        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
            int n = sc.nextInt();
            double ave = 0;
            double bun = 0;
            double bunm = 0;
            if(n == 0){
                break;
            }
            int[] ten = new int[n];
            for(int i = 0; i < ten.length;i++){
                ten[i] = sc.nextInt();
            }
            for(int i = 0;i <ten.length; i++){
                ave += ten[i];
            }
            ave = ave/ten.length;

            for(int i = 0;i < ten.length;i++){
                bunm = ten[i] - ave;
                bun += bunm*bunm;
            }
            bun = bun/ten.length;
            System.out.println(Math.sqrt(bun));
        } true {
            int n = sc.nextInt();
            double ave = 0;
            double bun = 0;
            double bunm = 0;
            if(n == 0){
                break;
            }
            int[] ten = new int[n];
            for(int i = 0; i < ten.length;i++){
                ten[i] = sc.nextInt();
            }
            for(int i = 0;i <ten.length; i++){
                ave += ten[i];
            }
            ave = ave/ten.length;

            for(int i = 0;i < ten.length;i++){
                bunm = ten[i] - ave;
                bun += bunm*bunm;
            }
            bun = bun/ten.length;
            System.out.println(Math.sqrt(bun));
        } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc double ave = 0; ave 0 double bun = 0; bun 0 double bunm = 0; bunm 0 if(n == 0){
                break;
            } n == 0 n 0 {
                break;
            } break; int[] ten = new int[n]; ten new int[n] n for(int i = 0; i < ten.length;i++){
                ten[i] = sc.nextInt();
            } int i = 0; int i = 0; i 0 i < ten.length i ten.length ten ten.length i++ i++ i {
                ten[i] = sc.nextInt();
            } {
                ten[i] = sc.nextInt();
            } ten[i] = sc.nextInt() ten[i] ten i sc.nextInt() sc.nextInt sc for(int i = 0;i <ten.length; i++){
                ave += ten[i];
            } int i = 0; int i = 0; i 0 i <ten.length i ten.length ten ten.length i++ i++ i {
                ave += ten[i];
            } {
                ave += ten[i];
            } ave += ten[i] ave ten[i] ten i ave = ave/ten.length ave ave/ten.length ave ten.length ten ten.length for(int i = 0;i < ten.length;i++){
                bunm = ten[i] - ave;
                bun += bunm*bunm;
            } int i = 0; int i = 0; i 0 i < ten.length i ten.length ten ten.length i++ i++ i {
                bunm = ten[i] - ave;
                bun += bunm*bunm;
            } {
                bunm = ten[i] - ave;
                bun += bunm*bunm;
            } bunm = ten[i] - ave bunm ten[i] - ave ten[i] ten i ave bun += bunm*bunm bun bunm*bunm bunm bunm bun = bun/ten.length bun bun/ten.length bun ten.length ten ten.length System.out.println(Math.sqrt(bun)) System.out.println System.out System System.out Math.sqrt(bun) Math.sqrt Math bun sc.close() sc.close sc String[] args args public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            double ave = 0;
            double bun = 0;
            double bunm = 0;
            if(n == 0){
                break;
            }
            int[] ten = new int[n];
            for(int i = 0; i < ten.length;i++){
                ten[i] = sc.nextInt();
            }
            for(int i = 0;i <ten.length; i++){
                ave += ten[i];
            }
            ave = ave/ten.length;

            for(int i = 0;i < ten.length;i++){
                bunm = ten[i] - ave;
                bun += bunm*bunm;
            }
            bun = bun/ten.length;
            System.out.println(Math.sqrt(bun));
        }
        sc.close();
    }
} public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            double ave = 0;
            double bun = 0;
            double bunm = 0;
            if(n == 0){
                break;
            }
            int[] ten = new int[n];
            for(int i = 0; i < ten.length;i++){
                ten[i] = sc.nextInt();
            }
            for(int i = 0;i <ten.length; i++){
                ave += ten[i];
            }
            ave = ave/ten.length;

            for(int i = 0;i < ten.length;i++){
                bunm = ten[i] - ave;
                bun += bunm*bunm;
            }
            bun = bun/ten.length;
            System.out.println(Math.sqrt(bun));
        }
        sc.close();
    }
} Main
import java.util.Scanner;

public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            double ave = 0;
            double bun = 0;
            double bunm = 0;
            if(n == 0){
                break;
            }
            int[] ten = new int[n];
            for(int i = 0; i < ten.length;i++){
                ten[i] = sc.nextInt();
            }
            for(int i = 0;i <ten.length; i++){
                ave += ten[i];
            }
            ave = ave/ten.length;

            for(int i = 0;i < ten.length;i++){
                bunm = ten[i] - ave;
                bun += bunm*bunm;
            }
            bun = bun/ten.length;
            System.out.println(Math.sqrt(bun));
        }
        sc.close();
    }
}
