
import java.util.Scanner;

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

        while(n!=0){
            double[] a = new double[n];
            double sum =0, ave;
            for(int i=0;i<n;i++){
                a[i]=scn.nextDouble();
                sum +=a[i];
            }
            ave = sum/n;
            sum=0;
            for(int i=0;i<n;i++){
                sum +=Math.pow(a[i]-ave,2);
            }
            ave = sum/n;
            double sd = Math.sqrt(ave);
            System.out.printf("%.8f%n",sd);
            n=scn.nextInt();

        }

        scn.close();

    }

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

        while(n!=0){
            double[] a = new double[n];
            double sum =0, ave;
            for(int i=0;i<n;i++){
                a[i]=scn.nextDouble();
                sum +=a[i];
            }
            ave = sum/n;
            sum=0;
            for(int i=0;i<n;i++){
                sum +=Math.pow(a[i]-ave,2);
            }
            ave = sum/n;
            double sd = Math.sqrt(ave);
            System.out.printf("%.8f%n",sd);
            n=scn.nextInt();

        }

        scn.close();

    }

} Main public static void main(String args[]) {
        Scanner scn = new Scanner(System.in);
        int n = scn.nextInt();

        while(n!=0){
            double[] a = new double[n];
            double sum =0, ave;
            for(int i=0;i<n;i++){
                a[i]=scn.nextDouble();
                sum +=a[i];
            }
            ave = sum/n;
            sum=0;
            for(int i=0;i<n;i++){
                sum +=Math.pow(a[i]-ave,2);
            }
            ave = sum/n;
            double sd = Math.sqrt(ave);
            System.out.printf("%.8f%n",sd);
            n=scn.nextInt();

        }

        scn.close();

    } main {
        Scanner scn = new Scanner(System.in);
        int n = scn.nextInt();

        while(n!=0){
            double[] a = new double[n];
            double sum =0, ave;
            for(int i=0;i<n;i++){
                a[i]=scn.nextDouble();
                sum +=a[i];
            }
            ave = sum/n;
            sum=0;
            for(int i=0;i<n;i++){
                sum +=Math.pow(a[i]-ave,2);
            }
            ave = sum/n;
            double sd = Math.sqrt(ave);
            System.out.printf("%.8f%n",sd);
            n=scn.nextInt();

        }

        scn.close();

    } Scanner scn = new Scanner(System.in); scn new Scanner(System.in) int n = scn.nextInt(); n scn.nextInt() scn.nextInt scn while(n!=0){
            double[] a = new double[n];
            double sum =0, ave;
            for(int i=0;i<n;i++){
                a[i]=scn.nextDouble();
                sum +=a[i];
            }
            ave = sum/n;
            sum=0;
            for(int i=0;i<n;i++){
                sum +=Math.pow(a[i]-ave,2);
            }
            ave = sum/n;
            double sd = Math.sqrt(ave);
            System.out.printf("%.8f%n",sd);
            n=scn.nextInt();

        } n!=0 n 0 {
            double[] a = new double[n];
            double sum =0, ave;
            for(int i=0;i<n;i++){
                a[i]=scn.nextDouble();
                sum +=a[i];
            }
            ave = sum/n;
            sum=0;
            for(int i=0;i<n;i++){
                sum +=Math.pow(a[i]-ave,2);
            }
            ave = sum/n;
            double sd = Math.sqrt(ave);
            System.out.printf("%.8f%n",sd);
            n=scn.nextInt();

        } double[] a = new double[n]; a new double[n] n double sum =0 sum 0 ave; ave for(int i=0;i<n;i++){
                a[i]=scn.nextDouble();
                sum +=a[i];
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                a[i]=scn.nextDouble();
                sum +=a[i];
            } {
                a[i]=scn.nextDouble();
                sum +=a[i];
            } a[i]=scn.nextDouble() a[i] a i scn.nextDouble() scn.nextDouble scn sum +=a[i] sum a[i] a i ave = sum/n ave sum/n sum n sum=0 sum 0 for(int i=0;i<n;i++){
                sum +=Math.pow(a[i]-ave,2);
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                sum +=Math.pow(a[i]-ave,2);
            } {
                sum +=Math.pow(a[i]-ave,2);
            } sum +=Math.pow(a[i]-ave,2) sum Math.pow(a[i]-ave,2) Math.pow Math a[i]-ave a[i] a i ave 2 ave = sum/n ave sum/n sum n double sd = Math.sqrt(ave); sd Math.sqrt(ave) Math.sqrt Math ave System.out.printf("%.8f%n",sd) System.out.printf System.out System System.out "%.8f%n" sd n=scn.nextInt() n scn.nextInt() scn.nextInt scn scn.close() scn.close scn String args[] args public class Main {
    public static void main(String args[]) {
        Scanner scn = new Scanner(System.in);
        int n = scn.nextInt();

        while(n!=0){
            double[] a = new double[n];
            double sum =0, ave;
            for(int i=0;i<n;i++){
                a[i]=scn.nextDouble();
                sum +=a[i];
            }
            ave = sum/n;
            sum=0;
            for(int i=0;i<n;i++){
                sum +=Math.pow(a[i]-ave,2);
            }
            ave = sum/n;
            double sd = Math.sqrt(ave);
            System.out.printf("%.8f%n",sd);
            n=scn.nextInt();

        }

        scn.close();

    }

} public class Main {
    public static void main(String args[]) {
        Scanner scn = new Scanner(System.in);
        int n = scn.nextInt();

        while(n!=0){
            double[] a = new double[n];
            double sum =0, ave;
            for(int i=0;i<n;i++){
                a[i]=scn.nextDouble();
                sum +=a[i];
            }
            ave = sum/n;
            sum=0;
            for(int i=0;i<n;i++){
                sum +=Math.pow(a[i]-ave,2);
            }
            ave = sum/n;
            double sd = Math.sqrt(ave);
            System.out.printf("%.8f%n",sd);
            n=scn.nextInt();

        }

        scn.close();

    }

} Main

import java.util.Scanner;

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

        while(n!=0){
            double[] a = new double[n];
            double sum =0, ave;
            for(int i=0;i<n;i++){
                a[i]=scn.nextDouble();
                sum +=a[i];
            }
            ave = sum/n;
            sum=0;
            for(int i=0;i<n;i++){
                sum +=Math.pow(a[i]-ave,2);
            }
            ave = sum/n;
            double sd = Math.sqrt(ave);
            System.out.printf("%.8f%n",sd);
            n=scn.nextInt();

        }

        scn.close();

    }

}
