import java.util.Scanner;
class Main{
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int n;
        int[] ary;
        double m, a2, sub;
        while(true){
            n = scanner.nextInt();
            if(n == 0)break;
            ary = new int[n];
            m = 0;
            a2 = 0;
            for(int i = 0; i < n; i++){
                ary[i] = scanner.nextInt();
                m += ary[i];
            }
            m /= n;
            for(int i = 0; i < n; i++){
                sub = ary[i] - m;
                a2 += sub*sub;
            }
            a2 /= n;
            System.out.println(Math.sqrt(a2));

        }

    }
}
 import java.util.Scanner; Scanner java.util class Main{
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int n;
        int[] ary;
        double m, a2, sub;
        while(true){
            n = scanner.nextInt();
            if(n == 0)break;
            ary = new int[n];
            m = 0;
            a2 = 0;
            for(int i = 0; i < n; i++){
                ary[i] = scanner.nextInt();
                m += ary[i];
            }
            m /= n;
            for(int i = 0; i < n; i++){
                sub = ary[i] - m;
                a2 += sub*sub;
            }
            a2 /= n;
            System.out.println(Math.sqrt(a2));

        }

    }
} Main public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int n;
        int[] ary;
        double m, a2, sub;
        while(true){
            n = scanner.nextInt();
            if(n == 0)break;
            ary = new int[n];
            m = 0;
            a2 = 0;
            for(int i = 0; i < n; i++){
                ary[i] = scanner.nextInt();
                m += ary[i];
            }
            m /= n;
            for(int i = 0; i < n; i++){
                sub = ary[i] - m;
                a2 += sub*sub;
            }
            a2 /= n;
            System.out.println(Math.sqrt(a2));

        }

    } main {
        Scanner scanner = new Scanner(System.in);
        int n;
        int[] ary;
        double m, a2, sub;
        while(true){
            n = scanner.nextInt();
            if(n == 0)break;
            ary = new int[n];
            m = 0;
            a2 = 0;
            for(int i = 0; i < n; i++){
                ary[i] = scanner.nextInt();
                m += ary[i];
            }
            m /= n;
            for(int i = 0; i < n; i++){
                sub = ary[i] - m;
                a2 += sub*sub;
            }
            a2 /= n;
            System.out.println(Math.sqrt(a2));

        }

    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int n; n int[] ary; ary double m m a2 a2 sub; sub while(true){
            n = scanner.nextInt();
            if(n == 0)break;
            ary = new int[n];
            m = 0;
            a2 = 0;
            for(int i = 0; i < n; i++){
                ary[i] = scanner.nextInt();
                m += ary[i];
            }
            m /= n;
            for(int i = 0; i < n; i++){
                sub = ary[i] - m;
                a2 += sub*sub;
            }
            a2 /= n;
            System.out.println(Math.sqrt(a2));

        } true {
            n = scanner.nextInt();
            if(n == 0)break;
            ary = new int[n];
            m = 0;
            a2 = 0;
            for(int i = 0; i < n; i++){
                ary[i] = scanner.nextInt();
                m += ary[i];
            }
            m /= n;
            for(int i = 0; i < n; i++){
                sub = ary[i] - m;
                a2 += sub*sub;
            }
            a2 /= n;
            System.out.println(Math.sqrt(a2));

        } n = scanner.nextInt() n scanner.nextInt() scanner.nextInt scanner if(n == 0)break; n == 0 n 0 break; ary = new int[n] ary new int[n] n m = 0 m 0 a2 = 0 a2 0 for(int i = 0; i < n; i++){
                ary[i] = scanner.nextInt();
                m += ary[i];
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                ary[i] = scanner.nextInt();
                m += ary[i];
            } {
                ary[i] = scanner.nextInt();
                m += ary[i];
            } ary[i] = scanner.nextInt() ary[i] ary i scanner.nextInt() scanner.nextInt scanner m += ary[i] m ary[i] ary i m /= n m n for(int i = 0; i < n; i++){
                sub = ary[i] - m;
                a2 += sub*sub;
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                sub = ary[i] - m;
                a2 += sub*sub;
            } {
                sub = ary[i] - m;
                a2 += sub*sub;
            } sub = ary[i] - m sub ary[i] - m ary[i] ary i m a2 += sub*sub a2 sub*sub sub sub a2 /= n a2 n System.out.println(Math.sqrt(a2)) System.out.println System.out System System.out Math.sqrt(a2) Math.sqrt Math a2 String[] args args
import java.util.Scanner;
class Main{
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int n;
        int[] ary;
        double m, a2, sub;
        while(true){
            n = scanner.nextInt();
            if(n == 0)break;
            ary = new int[n];
            m = 0;
            a2 = 0;
            for(int i = 0; i < n; i++){
                ary[i] = scanner.nextInt();
                m += ary[i];
            }
            m /= n;
            for(int i = 0; i < n; i++){
                sub = ary[i] - m;
                a2 += sub*sub;
            }
            a2 /= n;
            System.out.println(Math.sqrt(a2));

        }

    }
}

