import java.util.Scanner;
import java.lang.Math;
public class Main{
    public static void main(String[] args){
        int n;
        double sum = 0.0, m, v, t = 0.0;
        Scanner sc = new Scanner(System.in);
        
        while(true){
            n = sc.nextInt();
            if(n == 0) break;
            double A[] = new double[n];
            for(int i =0; i<A.length; i++){
                A[i] = (double)sc.nextInt();
                sum += A[i];
            }
            m = sum / (double)A.length;
            for(int i = 0; i<A.length; i++){
                t += (A[i] - m) * (A[i] - m);
            }
            v = t / (double)A.length;
            System.out.println(Math.sqrt(v));
            sum = 0.0;
            t = 0.0;
        }
    }
} import java.util.Scanner; Scanner java.util import java.lang.Math; Math java.lang public class Main{
    public static void main(String[] args){
        int n;
        double sum = 0.0, m, v, t = 0.0;
        Scanner sc = new Scanner(System.in);
        
        while(true){
            n = sc.nextInt();
            if(n == 0) break;
            double A[] = new double[n];
            for(int i =0; i<A.length; i++){
                A[i] = (double)sc.nextInt();
                sum += A[i];
            }
            m = sum / (double)A.length;
            for(int i = 0; i<A.length; i++){
                t += (A[i] - m) * (A[i] - m);
            }
            v = t / (double)A.length;
            System.out.println(Math.sqrt(v));
            sum = 0.0;
            t = 0.0;
        }
    }
} Main public static void main(String[] args){
        int n;
        double sum = 0.0, m, v, t = 0.0;
        Scanner sc = new Scanner(System.in);
        
        while(true){
            n = sc.nextInt();
            if(n == 0) break;
            double A[] = new double[n];
            for(int i =0; i<A.length; i++){
                A[i] = (double)sc.nextInt();
                sum += A[i];
            }
            m = sum / (double)A.length;
            for(int i = 0; i<A.length; i++){
                t += (A[i] - m) * (A[i] - m);
            }
            v = t / (double)A.length;
            System.out.println(Math.sqrt(v));
            sum = 0.0;
            t = 0.0;
        }
    } main {
        int n;
        double sum = 0.0, m, v, t = 0.0;
        Scanner sc = new Scanner(System.in);
        
        while(true){
            n = sc.nextInt();
            if(n == 0) break;
            double A[] = new double[n];
            for(int i =0; i<A.length; i++){
                A[i] = (double)sc.nextInt();
                sum += A[i];
            }
            m = sum / (double)A.length;
            for(int i = 0; i<A.length; i++){
                t += (A[i] - m) * (A[i] - m);
            }
            v = t / (double)A.length;
            System.out.println(Math.sqrt(v));
            sum = 0.0;
            t = 0.0;
        }
    } int n; n double sum = 0.0 sum 0.0 m m v v t = 0.0; t 0.0 Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
            n = sc.nextInt();
            if(n == 0) break;
            double A[] = new double[n];
            for(int i =0; i<A.length; i++){
                A[i] = (double)sc.nextInt();
                sum += A[i];
            }
            m = sum / (double)A.length;
            for(int i = 0; i<A.length; i++){
                t += (A[i] - m) * (A[i] - m);
            }
            v = t / (double)A.length;
            System.out.println(Math.sqrt(v));
            sum = 0.0;
            t = 0.0;
        } true {
            n = sc.nextInt();
            if(n == 0) break;
            double A[] = new double[n];
            for(int i =0; i<A.length; i++){
                A[i] = (double)sc.nextInt();
                sum += A[i];
            }
            m = sum / (double)A.length;
            for(int i = 0; i<A.length; i++){
                t += (A[i] - m) * (A[i] - m);
            }
            v = t / (double)A.length;
            System.out.println(Math.sqrt(v));
            sum = 0.0;
            t = 0.0;
        } n = sc.nextInt() n sc.nextInt() sc.nextInt sc if(n == 0) break; n == 0 n 0 break; double A[] = new double[n]; A new double[n] n for(int i =0; i<A.length; i++){
                A[i] = (double)sc.nextInt();
                sum += A[i];
            } int i =0; int i =0; i 0 i<A.length i A.length A A.length i++ i++ i {
                A[i] = (double)sc.nextInt();
                sum += A[i];
            } {
                A[i] = (double)sc.nextInt();
                sum += A[i];
            } A[i] = (double)sc.nextInt() A[i] A i (double)sc.nextInt() sc.nextInt sc sum += A[i] sum A[i] A i m = sum / (double)A.length m sum / (double)A.length sum (double)A.length A A.length for(int i = 0; i<A.length; i++){
                t += (A[i] - m) * (A[i] - m);
            } int i = 0; int i = 0; i 0 i<A.length i A.length A A.length i++ i++ i {
                t += (A[i] - m) * (A[i] - m);
            } {
                t += (A[i] - m) * (A[i] - m);
            } t += (A[i] - m) * (A[i] - m) t (A[i] - m) * (A[i] - m) (A[i] - m) A[i] A i m (A[i] - m) A[i] A i m v = t / (double)A.length v t / (double)A.length t (double)A.length A A.length System.out.println(Math.sqrt(v)) System.out.println System.out System System.out Math.sqrt(v) Math.sqrt Math v sum = 0.0 sum 0.0 t = 0.0 t 0.0 String[] args args public class Main{
    public static void main(String[] args){
        int n;
        double sum = 0.0, m, v, t = 0.0;
        Scanner sc = new Scanner(System.in);
        
        while(true){
            n = sc.nextInt();
            if(n == 0) break;
            double A[] = new double[n];
            for(int i =0; i<A.length; i++){
                A[i] = (double)sc.nextInt();
                sum += A[i];
            }
            m = sum / (double)A.length;
            for(int i = 0; i<A.length; i++){
                t += (A[i] - m) * (A[i] - m);
            }
            v = t / (double)A.length;
            System.out.println(Math.sqrt(v));
            sum = 0.0;
            t = 0.0;
        }
    }
} public class Main{
    public static void main(String[] args){
        int n;
        double sum = 0.0, m, v, t = 0.0;
        Scanner sc = new Scanner(System.in);
        
        while(true){
            n = sc.nextInt();
            if(n == 0) break;
            double A[] = new double[n];
            for(int i =0; i<A.length; i++){
                A[i] = (double)sc.nextInt();
                sum += A[i];
            }
            m = sum / (double)A.length;
            for(int i = 0; i<A.length; i++){
                t += (A[i] - m) * (A[i] - m);
            }
            v = t / (double)A.length;
            System.out.println(Math.sqrt(v));
            sum = 0.0;
            t = 0.0;
        }
    }
} Main
import java.util.Scanner;
import java.lang.Math;
public class Main{
    public static void main(String[] args){
        int n;
        double sum = 0.0, m, v, t = 0.0;
        Scanner sc = new Scanner(System.in);
        
        while(true){
            n = sc.nextInt();
            if(n == 0) break;
            double A[] = new double[n];
            for(int i =0; i<A.length; i++){
                A[i] = (double)sc.nextInt();
                sum += A[i];
            }
            m = sum / (double)A.length;
            for(int i = 0; i<A.length; i++){
                t += (A[i] - m) * (A[i] - m);
            }
            v = t / (double)A.length;
            System.out.println(Math.sqrt(v));
            sum = 0.0;
            t = 0.0;
        }
    }
}
