import java.util.Scanner;

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

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