import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
        int num = sc.nextInt();
        if(num == 0) break;
        int[] array = new int[num];
        int sum = 0;
        for(int i = 0; i < num; i++){
            array[i] = sc.nextInt();
            sum += array[i];
        }
        double a = 0;
        for(int i = 0; i < num; i++){
            a += Math.pow(array[i] - sum / (double)num, 2);
        }
        a = a / (double)num;
        
        System.out.println(Math.sqrt(a));
        }
    }
} 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 num = sc.nextInt();
        if(num == 0) break;
        int[] array = new int[num];
        int sum = 0;
        for(int i = 0; i < num; i++){
            array[i] = sc.nextInt();
            sum += array[i];
        }
        double a = 0;
        for(int i = 0; i < num; i++){
            a += Math.pow(array[i] - sum / (double)num, 2);
        }
        a = a / (double)num;
        
        System.out.println(Math.sqrt(a));
        }
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
        int num = sc.nextInt();
        if(num == 0) break;
        int[] array = new int[num];
        int sum = 0;
        for(int i = 0; i < num; i++){
            array[i] = sc.nextInt();
            sum += array[i];
        }
        double a = 0;
        for(int i = 0; i < num; i++){
            a += Math.pow(array[i] - sum / (double)num, 2);
        }
        a = a / (double)num;
        
        System.out.println(Math.sqrt(a));
        }
    } main {
        Scanner sc = new Scanner(System.in);
        while(true){
        int num = sc.nextInt();
        if(num == 0) break;
        int[] array = new int[num];
        int sum = 0;
        for(int i = 0; i < num; i++){
            array[i] = sc.nextInt();
            sum += array[i];
        }
        double a = 0;
        for(int i = 0; i < num; i++){
            a += Math.pow(array[i] - sum / (double)num, 2);
        }
        a = a / (double)num;
        
        System.out.println(Math.sqrt(a));
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
        int num = sc.nextInt();
        if(num == 0) break;
        int[] array = new int[num];
        int sum = 0;
        for(int i = 0; i < num; i++){
            array[i] = sc.nextInt();
            sum += array[i];
        }
        double a = 0;
        for(int i = 0; i < num; i++){
            a += Math.pow(array[i] - sum / (double)num, 2);
        }
        a = a / (double)num;
        
        System.out.println(Math.sqrt(a));
        } true {
        int num = sc.nextInt();
        if(num == 0) break;
        int[] array = new int[num];
        int sum = 0;
        for(int i = 0; i < num; i++){
            array[i] = sc.nextInt();
            sum += array[i];
        }
        double a = 0;
        for(int i = 0; i < num; i++){
            a += Math.pow(array[i] - sum / (double)num, 2);
        }
        a = a / (double)num;
        
        System.out.println(Math.sqrt(a));
        } int num = sc.nextInt(); num sc.nextInt() sc.nextInt sc if(num == 0) break; num == 0 num 0 break; int[] array = new int[num]; array new int[num] num int sum = 0; sum 0 for(int i = 0; i < num; i++){
            array[i] = sc.nextInt();
            sum += array[i];
        } int i = 0; int i = 0; i 0 i < num i num i++ i++ i {
            array[i] = sc.nextInt();
            sum += array[i];
        } {
            array[i] = sc.nextInt();
            sum += array[i];
        } array[i] = sc.nextInt() array[i] array i sc.nextInt() sc.nextInt sc sum += array[i] sum array[i] array i double a = 0; a 0 for(int i = 0; i < num; i++){
            a += Math.pow(array[i] - sum / (double)num, 2);
        } int i = 0; int i = 0; i 0 i < num i num i++ i++ i {
            a += Math.pow(array[i] - sum / (double)num, 2);
        } {
            a += Math.pow(array[i] - sum / (double)num, 2);
        } a += Math.pow(array[i] - sum / (double)num, 2) a Math.pow(array[i] - sum / (double)num, 2) Math.pow Math array[i] - sum / (double)num array[i] array i sum / (double)num sum (double)num 2 a = a / (double)num a a / (double)num a (double)num System.out.println(Math.sqrt(a)) System.out.println System.out System System.out Math.sqrt(a) Math.sqrt Math a String[] args args public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
        int num = sc.nextInt();
        if(num == 0) break;
        int[] array = new int[num];
        int sum = 0;
        for(int i = 0; i < num; i++){
            array[i] = sc.nextInt();
            sum += array[i];
        }
        double a = 0;
        for(int i = 0; i < num; i++){
            a += Math.pow(array[i] - sum / (double)num, 2);
        }
        a = a / (double)num;
        
        System.out.println(Math.sqrt(a));
        }
    }
} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
        int num = sc.nextInt();
        if(num == 0) break;
        int[] array = new int[num];
        int sum = 0;
        for(int i = 0; i < num; i++){
            array[i] = sc.nextInt();
            sum += array[i];
        }
        double a = 0;
        for(int i = 0; i < num; i++){
            a += Math.pow(array[i] - sum / (double)num, 2);
        }
        a = a / (double)num;
        
        System.out.println(Math.sqrt(a));
        }
    }
} Main
import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
        int num = sc.nextInt();
        if(num == 0) break;
        int[] array = new int[num];
        int sum = 0;
        for(int i = 0; i < num; i++){
            array[i] = sc.nextInt();
            sum += array[i];
        }
        double a = 0;
        for(int i = 0; i < num; i++){
            a += Math.pow(array[i] - sum / (double)num, 2);
        }
        a = a / (double)num;
        
        System.out.println(Math.sqrt(a));
        }
    }
}
