import java.util.Scanner;

public class Main{

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

        while (true) {
            int n=sc.nextInt();
            int[] num;
            int sum=0;
            num=new int[n];

            if (n==0) {
                break;
            }

            for(int i=0;i<n;i++){
                num[i]=sc.nextInt();
                sum+=num[i];
            }
            double ave=(double)sum/n;

            double div=0.0;
            for(int i=0;i<n;i++){
                div+=Math.pow((num[i]-ave),2);

            }
            double a=Math.sqrt(div/n);
            System.out.println(a);
        }

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

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

        while (true) {
            int n=sc.nextInt();
            int[] num;
            int sum=0;
            num=new int[n];

            if (n==0) {
                break;
            }

            for(int i=0;i<n;i++){
                num[i]=sc.nextInt();
                sum+=num[i];
            }
            double ave=(double)sum/n;

            double div=0.0;
            for(int i=0;i<n;i++){
                div+=Math.pow((num[i]-ave),2);

            }
            double a=Math.sqrt(div/n);
            System.out.println(a);
        }

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

        while (true) {
            int n=sc.nextInt();
            int[] num;
            int sum=0;
            num=new int[n];

            if (n==0) {
                break;
            }

            for(int i=0;i<n;i++){
                num[i]=sc.nextInt();
                sum+=num[i];
            }
            double ave=(double)sum/n;

            double div=0.0;
            for(int i=0;i<n;i++){
                div+=Math.pow((num[i]-ave),2);

            }
            double a=Math.sqrt(div/n);
            System.out.println(a);
        }

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

        while (true) {
            int n=sc.nextInt();
            int[] num;
            int sum=0;
            num=new int[n];

            if (n==0) {
                break;
            }

            for(int i=0;i<n;i++){
                num[i]=sc.nextInt();
                sum+=num[i];
            }
            double ave=(double)sum/n;

            double div=0.0;
            for(int i=0;i<n;i++){
                div+=Math.pow((num[i]-ave),2);

            }
            double a=Math.sqrt(div/n);
            System.out.println(a);
        }

        sc.close();
    
    } Scanner sc=new Scanner(System.in); sc new Scanner(System.in) while (true) {
            int n=sc.nextInt();
            int[] num;
            int sum=0;
            num=new int[n];

            if (n==0) {
                break;
            }

            for(int i=0;i<n;i++){
                num[i]=sc.nextInt();
                sum+=num[i];
            }
            double ave=(double)sum/n;

            double div=0.0;
            for(int i=0;i<n;i++){
                div+=Math.pow((num[i]-ave),2);

            }
            double a=Math.sqrt(div/n);
            System.out.println(a);
        } true {
            int n=sc.nextInt();
            int[] num;
            int sum=0;
            num=new int[n];

            if (n==0) {
                break;
            }

            for(int i=0;i<n;i++){
                num[i]=sc.nextInt();
                sum+=num[i];
            }
            double ave=(double)sum/n;

            double div=0.0;
            for(int i=0;i<n;i++){
                div+=Math.pow((num[i]-ave),2);

            }
            double a=Math.sqrt(div/n);
            System.out.println(a);
        } int n=sc.nextInt(); n sc.nextInt() sc.nextInt sc int[] num; num int sum=0; sum 0 num=new int[n] num new int[n] n if (n==0) {
                break;
            } n==0 n 0 {
                break;
            } break; for(int i=0;i<n;i++){
                num[i]=sc.nextInt();
                sum+=num[i];
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                num[i]=sc.nextInt();
                sum+=num[i];
            } {
                num[i]=sc.nextInt();
                sum+=num[i];
            } num[i]=sc.nextInt() num[i] num i sc.nextInt() sc.nextInt sc sum+=num[i] sum num[i] num i double ave=(double)sum/n; ave (double)sum/n (double)sum n double div=0.0; div 0.0 for(int i=0;i<n;i++){
                div+=Math.pow((num[i]-ave),2);

            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                div+=Math.pow((num[i]-ave),2);

            } {
                div+=Math.pow((num[i]-ave),2);

            } div+=Math.pow((num[i]-ave),2) div Math.pow((num[i]-ave),2) Math.pow Math (num[i]-ave) num[i] num i ave 2 double a=Math.sqrt(div/n); a Math.sqrt(div/n) Math.sqrt Math div/n div n System.out.println(a) System.out.println System.out System System.out a sc.close() sc.close sc String[] args args public class Main{

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

        while (true) {
            int n=sc.nextInt();
            int[] num;
            int sum=0;
            num=new int[n];

            if (n==0) {
                break;
            }

            for(int i=0;i<n;i++){
                num[i]=sc.nextInt();
                sum+=num[i];
            }
            double ave=(double)sum/n;

            double div=0.0;
            for(int i=0;i<n;i++){
                div+=Math.pow((num[i]-ave),2);

            }
            double a=Math.sqrt(div/n);
            System.out.println(a);
        }

        sc.close();
    
    }
    
} public class Main{

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

        while (true) {
            int n=sc.nextInt();
            int[] num;
            int sum=0;
            num=new int[n];

            if (n==0) {
                break;
            }

            for(int i=0;i<n;i++){
                num[i]=sc.nextInt();
                sum+=num[i];
            }
            double ave=(double)sum/n;

            double div=0.0;
            for(int i=0;i<n;i++){
                div+=Math.pow((num[i]-ave),2);

            }
            double a=Math.sqrt(div/n);
            System.out.println(a);
        }

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

public class Main{

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

        while (true) {
            int n=sc.nextInt();
            int[] num;
            int sum=0;
            num=new int[n];

            if (n==0) {
                break;
            }

            for(int i=0;i<n;i++){
                num[i]=sc.nextInt();
                sum+=num[i];
            }
            double ave=(double)sum/n;

            double div=0.0;
            for(int i=0;i<n;i++){
                div+=Math.pow((num[i]-ave),2);

            }
            double a=Math.sqrt(div/n);
            System.out.println(a);
        }

        sc.close();
    
    }
    
}
