import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        double[] std = new double[100];
        int cnt=0;
        double sum=0;
        double mean;
        while(true){
            int n;
            n = sc.nextInt();
            if(n == 0)
                break;
            sum=0;
            mean=0;
            double[] s = new double[n];
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            mean = sum/n;
            sum = 0;
            for(int i=0; i<n; i++){
                sum += Math.pow((s[i] - mean), 2); 
            }
            mean = sum/n;
            std[cnt] = Math.sqrt(mean);
            cnt++;
        }

        for(int i=0; i<cnt; i++){
            System.out.printf("%.8f\n", std[i]);
        }

        sc.close();
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        double[] std = new double[100];
        int cnt=0;
        double sum=0;
        double mean;
        while(true){
            int n;
            n = sc.nextInt();
            if(n == 0)
                break;
            sum=0;
            mean=0;
            double[] s = new double[n];
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            mean = sum/n;
            sum = 0;
            for(int i=0; i<n; i++){
                sum += Math.pow((s[i] - mean), 2); 
            }
            mean = sum/n;
            std[cnt] = Math.sqrt(mean);
            cnt++;
        }

        for(int i=0; i<cnt; i++){
            System.out.printf("%.8f\n", std[i]);
        }

        sc.close();
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        double[] std = new double[100];
        int cnt=0;
        double sum=0;
        double mean;
        while(true){
            int n;
            n = sc.nextInt();
            if(n == 0)
                break;
            sum=0;
            mean=0;
            double[] s = new double[n];
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            mean = sum/n;
            sum = 0;
            for(int i=0; i<n; i++){
                sum += Math.pow((s[i] - mean), 2); 
            }
            mean = sum/n;
            std[cnt] = Math.sqrt(mean);
            cnt++;
        }

        for(int i=0; i<cnt; i++){
            System.out.printf("%.8f\n", std[i]);
        }

        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);

        double[] std = new double[100];
        int cnt=0;
        double sum=0;
        double mean;
        while(true){
            int n;
            n = sc.nextInt();
            if(n == 0)
                break;
            sum=0;
            mean=0;
            double[] s = new double[n];
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            mean = sum/n;
            sum = 0;
            for(int i=0; i<n; i++){
                sum += Math.pow((s[i] - mean), 2); 
            }
            mean = sum/n;
            std[cnt] = Math.sqrt(mean);
            cnt++;
        }

        for(int i=0; i<cnt; i++){
            System.out.printf("%.8f\n", std[i]);
        }

        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double[] std = new double[100]; std new double[100] 100 int cnt=0; cnt 0 double sum=0; sum 0 double mean; mean while(true){
            int n;
            n = sc.nextInt();
            if(n == 0)
                break;
            sum=0;
            mean=0;
            double[] s = new double[n];
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            mean = sum/n;
            sum = 0;
            for(int i=0; i<n; i++){
                sum += Math.pow((s[i] - mean), 2); 
            }
            mean = sum/n;
            std[cnt] = Math.sqrt(mean);
            cnt++;
        } true {
            int n;
            n = sc.nextInt();
            if(n == 0)
                break;
            sum=0;
            mean=0;
            double[] s = new double[n];
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            mean = sum/n;
            sum = 0;
            for(int i=0; i<n; i++){
                sum += Math.pow((s[i] - mean), 2); 
            }
            mean = sum/n;
            std[cnt] = Math.sqrt(mean);
            cnt++;
        } int n; n n = sc.nextInt() n sc.nextInt() sc.nextInt sc if(n == 0)
                break; n == 0 n 0 break; sum=0 sum 0 mean=0 mean 0 double[] s = new double[n]; s new double[n] n 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 mean = sum/n mean sum/n sum n sum = 0 sum 0 for(int i=0; i<n; i++){
                sum += Math.pow((s[i] - mean), 2); 
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                sum += Math.pow((s[i] - mean), 2); 
            } {
                sum += Math.pow((s[i] - mean), 2); 
            } sum += Math.pow((s[i] - mean), 2) sum Math.pow((s[i] - mean), 2) Math.pow Math (s[i] - mean) s[i] s i mean 2 mean = sum/n mean sum/n sum n std[cnt] = Math.sqrt(mean) std[cnt] std cnt Math.sqrt(mean) Math.sqrt Math mean cnt++ cnt for(int i=0; i<cnt; i++){
            System.out.printf("%.8f\n", std[i]);
        } int i=0; int i=0; i 0 i<cnt i cnt i++ i++ i {
            System.out.printf("%.8f\n", std[i]);
        } {
            System.out.printf("%.8f\n", std[i]);
        } System.out.printf("%.8f\n", std[i]) System.out.printf System.out System System.out "%.8f\n" std[i] std i sc.close() sc.close sc String[] args args public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        double[] std = new double[100];
        int cnt=0;
        double sum=0;
        double mean;
        while(true){
            int n;
            n = sc.nextInt();
            if(n == 0)
                break;
            sum=0;
            mean=0;
            double[] s = new double[n];
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            mean = sum/n;
            sum = 0;
            for(int i=0; i<n; i++){
                sum += Math.pow((s[i] - mean), 2); 
            }
            mean = sum/n;
            std[cnt] = Math.sqrt(mean);
            cnt++;
        }

        for(int i=0; i<cnt; i++){
            System.out.printf("%.8f\n", std[i]);
        }

        sc.close();
    }
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        double[] std = new double[100];
        int cnt=0;
        double sum=0;
        double mean;
        while(true){
            int n;
            n = sc.nextInt();
            if(n == 0)
                break;
            sum=0;
            mean=0;
            double[] s = new double[n];
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            mean = sum/n;
            sum = 0;
            for(int i=0; i<n; i++){
                sum += Math.pow((s[i] - mean), 2); 
            }
            mean = sum/n;
            std[cnt] = Math.sqrt(mean);
            cnt++;
        }

        for(int i=0; i<cnt; i++){
            System.out.printf("%.8f\n", std[i]);
        }

        sc.close();
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        double[] std = new double[100];
        int cnt=0;
        double sum=0;
        double mean;
        while(true){
            int n;
            n = sc.nextInt();
            if(n == 0)
                break;
            sum=0;
            mean=0;
            double[] s = new double[n];
            for(int i=0; i<n; i++){
                s[i] = sc.nextInt();
                sum += s[i];
            }
            mean = sum/n;
            sum = 0;
            for(int i=0; i<n; i++){
                sum += Math.pow((s[i] - mean), 2); 
            }
            mean = sum/n;
            std[cnt] = Math.sqrt(mean);
            cnt++;
        }

        for(int i=0; i<cnt; i++){
            System.out.printf("%.8f\n", std[i]);
        }

        sc.close();
    }
}
