import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Here your code !
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int s[] = new int[1000];
        double sum=0.0, avg,alpha;
        
        while(n!=0){
            sum = 0.0;
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            avg = sum/n;
            sum = 0.0;
            for(int i=0; i<n; i++){
                sum += (s[i] - avg)*(s[i] - avg);
            }
            alpha = Math.sqrt(sum/n);
            System.out.println(alpha);
            n = sc.nextInt();
        }
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        // Here your code !
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int s[] = new int[1000];
        double sum=0.0, avg,alpha;
        
        while(n!=0){
            sum = 0.0;
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            avg = sum/n;
            sum = 0.0;
            for(int i=0; i<n; i++){
                sum += (s[i] - avg)*(s[i] - avg);
            }
            alpha = Math.sqrt(sum/n);
            System.out.println(alpha);
            n = sc.nextInt();
        }
    }
} Main public static void main(String[] args) throws Exception {
        // Here your code !
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int s[] = new int[1000];
        double sum=0.0, avg,alpha;
        
        while(n!=0){
            sum = 0.0;
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            avg = sum/n;
            sum = 0.0;
            for(int i=0; i<n; i++){
                sum += (s[i] - avg)*(s[i] - avg);
            }
            alpha = Math.sqrt(sum/n);
            System.out.println(alpha);
            n = sc.nextInt();
        }
    } main {
        // Here your code !
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int s[] = new int[1000];
        double sum=0.0, avg,alpha;
        
        while(n!=0){
            sum = 0.0;
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            avg = sum/n;
            sum = 0.0;
            for(int i=0; i<n; i++){
                sum += (s[i] - avg)*(s[i] - avg);
            }
            alpha = Math.sqrt(sum/n);
            System.out.println(alpha);
            n = sc.nextInt();
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int s[] = new int[1000]; s new int[1000] 1000 double sum=0.0 sum 0.0 avg avg alpha; alpha while(n!=0){
            sum = 0.0;
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            avg = sum/n;
            sum = 0.0;
            for(int i=0; i<n; i++){
                sum += (s[i] - avg)*(s[i] - avg);
            }
            alpha = Math.sqrt(sum/n);
            System.out.println(alpha);
            n = sc.nextInt();
        } n!=0 n 0 {
            sum = 0.0;
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            avg = sum/n;
            sum = 0.0;
            for(int i=0; i<n; i++){
                sum += (s[i] - avg)*(s[i] - avg);
            }
            alpha = Math.sqrt(sum/n);
            System.out.println(alpha);
            n = sc.nextInt();
        } sum = 0.0 sum 0.0 for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                s[i] = sc.nextInt();
                sum += s[i];
            } {
                s[i] = sc.nextInt();
                sum += s[i];
            } s[i] = sc.nextInt() s[i] s i sc.nextInt() sc.nextInt sc sum += s[i] sum s[i] s i avg = sum/n avg sum/n sum n sum = 0.0 sum 0.0 for(int i=0; i<n; i++){
                sum += (s[i] - avg)*(s[i] - avg);
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                sum += (s[i] - avg)*(s[i] - avg);
            } {
                sum += (s[i] - avg)*(s[i] - avg);
            } sum += (s[i] - avg)*(s[i] - avg) sum (s[i] - avg)*(s[i] - avg) (s[i] - avg) s[i] s i avg (s[i] - avg) s[i] s i avg alpha = Math.sqrt(sum/n) alpha Math.sqrt(sum/n) Math.sqrt Math sum/n sum n System.out.println(alpha) System.out.println System.out System System.out alpha n = sc.nextInt() n sc.nextInt() sc.nextInt sc String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        // Here your code !
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int s[] = new int[1000];
        double sum=0.0, avg,alpha;
        
        while(n!=0){
            sum = 0.0;
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            avg = sum/n;
            sum = 0.0;
            for(int i=0; i<n; i++){
                sum += (s[i] - avg)*(s[i] - avg);
            }
            alpha = Math.sqrt(sum/n);
            System.out.println(alpha);
            n = sc.nextInt();
        }
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        // Here your code !
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int s[] = new int[1000];
        double sum=0.0, avg,alpha;
        
        while(n!=0){
            sum = 0.0;
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            avg = sum/n;
            sum = 0.0;
            for(int i=0; i<n; i++){
                sum += (s[i] - avg)*(s[i] - avg);
            }
            alpha = Math.sqrt(sum/n);
            System.out.println(alpha);
            n = sc.nextInt();
        }
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Here your code !
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int s[] = new int[1000];
        double sum=0.0, avg,alpha;
        
        while(n!=0){
            sum = 0.0;
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            avg = sum/n;
            sum = 0.0;
            for(int i=0; i<n; i++){
                sum += (s[i] - avg)*(s[i] - avg);
            }
            alpha = Math.sqrt(sum/n);
            System.out.println(alpha);
            n = sc.nextInt();
        }
    }
}