import java.util.Scanner;

import static java.lang.Math.pow;
import static java.lang.Math.sqrt;

class Main{
    
    public static void main(String[] arg){

        Scanner in = new Scanner(System.in);

        String input = in.nextLine();

        int cnt = Integer.parseInt(input);

        while(cnt != 0){
            double sum = 0.0;
            input = in.nextLine();
            String [] param_line = input.split(" ", 0);
            int [] points = new int[param_line.length];
            for(int i=0; i<points.length; i++){
                points[i] = Integer.parseInt(param_line[i]);
                sum += points[i];
            }

            double avg = sum/points.length;
            double tmp = 0;
            for(int i=0; i<points.length; i++)
                tmp += pow(points[i]-avg,2);

            double bunsan = tmp/points.length;
            double hyohen = sqrt(bunsan);

            System.out.printf("%.8f\n",hyohen);

            input = in.nextLine();
            cnt = Integer.parseInt(input);
        }
    }
} import java.util.Scanner; Scanner java.util import static java.lang.Math.pow; import static java.lang.Math.pow; import static java.lang.Math.pow; import static java.lang.Math.sqrt; import static java.lang.Math.sqrt; import static java.lang.Math.sqrt; class Main{
    
    public static void main(String[] arg){

        Scanner in = new Scanner(System.in);

        String input = in.nextLine();

        int cnt = Integer.parseInt(input);

        while(cnt != 0){
            double sum = 0.0;
            input = in.nextLine();
            String [] param_line = input.split(" ", 0);
            int [] points = new int[param_line.length];
            for(int i=0; i<points.length; i++){
                points[i] = Integer.parseInt(param_line[i]);
                sum += points[i];
            }

            double avg = sum/points.length;
            double tmp = 0;
            for(int i=0; i<points.length; i++)
                tmp += pow(points[i]-avg,2);

            double bunsan = tmp/points.length;
            double hyohen = sqrt(bunsan);

            System.out.printf("%.8f\n",hyohen);

            input = in.nextLine();
            cnt = Integer.parseInt(input);
        }
    }
} Main public static void main(String[] arg){

        Scanner in = new Scanner(System.in);

        String input = in.nextLine();

        int cnt = Integer.parseInt(input);

        while(cnt != 0){
            double sum = 0.0;
            input = in.nextLine();
            String [] param_line = input.split(" ", 0);
            int [] points = new int[param_line.length];
            for(int i=0; i<points.length; i++){
                points[i] = Integer.parseInt(param_line[i]);
                sum += points[i];
            }

            double avg = sum/points.length;
            double tmp = 0;
            for(int i=0; i<points.length; i++)
                tmp += pow(points[i]-avg,2);

            double bunsan = tmp/points.length;
            double hyohen = sqrt(bunsan);

            System.out.printf("%.8f\n",hyohen);

            input = in.nextLine();
            cnt = Integer.parseInt(input);
        }
    } main {

        Scanner in = new Scanner(System.in);

        String input = in.nextLine();

        int cnt = Integer.parseInt(input);

        while(cnt != 0){
            double sum = 0.0;
            input = in.nextLine();
            String [] param_line = input.split(" ", 0);
            int [] points = new int[param_line.length];
            for(int i=0; i<points.length; i++){
                points[i] = Integer.parseInt(param_line[i]);
                sum += points[i];
            }

            double avg = sum/points.length;
            double tmp = 0;
            for(int i=0; i<points.length; i++)
                tmp += pow(points[i]-avg,2);

            double bunsan = tmp/points.length;
            double hyohen = sqrt(bunsan);

            System.out.printf("%.8f\n",hyohen);

            input = in.nextLine();
            cnt = Integer.parseInt(input);
        }
    } Scanner in = new Scanner(System.in); in new Scanner(System.in) String input = in.nextLine(); input in.nextLine() in.nextLine in int cnt = Integer.parseInt(input); cnt Integer.parseInt(input) Integer.parseInt Integer input while(cnt != 0){
            double sum = 0.0;
            input = in.nextLine();
            String [] param_line = input.split(" ", 0);
            int [] points = new int[param_line.length];
            for(int i=0; i<points.length; i++){
                points[i] = Integer.parseInt(param_line[i]);
                sum += points[i];
            }

            double avg = sum/points.length;
            double tmp = 0;
            for(int i=0; i<points.length; i++)
                tmp += pow(points[i]-avg,2);

            double bunsan = tmp/points.length;
            double hyohen = sqrt(bunsan);

            System.out.printf("%.8f\n",hyohen);

            input = in.nextLine();
            cnt = Integer.parseInt(input);
        } cnt != 0 cnt 0 {
            double sum = 0.0;
            input = in.nextLine();
            String [] param_line = input.split(" ", 0);
            int [] points = new int[param_line.length];
            for(int i=0; i<points.length; i++){
                points[i] = Integer.parseInt(param_line[i]);
                sum += points[i];
            }

            double avg = sum/points.length;
            double tmp = 0;
            for(int i=0; i<points.length; i++)
                tmp += pow(points[i]-avg,2);

            double bunsan = tmp/points.length;
            double hyohen = sqrt(bunsan);

            System.out.printf("%.8f\n",hyohen);

            input = in.nextLine();
            cnt = Integer.parseInt(input);
        } double sum = 0.0; sum 0.0 input = in.nextLine() input in.nextLine() in.nextLine in String [] param_line = input.split(" ", 0); param_line input.split(" ", 0) input.split input " " 0 int [] points = new int[param_line.length]; points new int[param_line.length] param_line.length param_line param_line.length for(int i=0; i<points.length; i++){
                points[i] = Integer.parseInt(param_line[i]);
                sum += points[i];
            } int i=0; int i=0; i 0 i<points.length i points.length points points.length i++ i++ i {
                points[i] = Integer.parseInt(param_line[i]);
                sum += points[i];
            } {
                points[i] = Integer.parseInt(param_line[i]);
                sum += points[i];
            } points[i] = Integer.parseInt(param_line[i]) points[i] points i Integer.parseInt(param_line[i]) Integer.parseInt Integer param_line[i] param_line i sum += points[i] sum points[i] points i double avg = sum/points.length; avg sum/points.length sum points.length points points.length double tmp = 0; tmp 0 for(int i=0; i<points.length; i++)
                tmp += pow(points[i]-avg,2); int i=0; int i=0; i 0 i<points.length i points.length points points.length i++ i++ i tmp += pow(points[i]-avg,2); tmp += pow(points[i]-avg,2) tmp pow(points[i]-avg,2) pow points[i]-avg points[i] points i avg 2 double bunsan = tmp/points.length; bunsan tmp/points.length tmp points.length points points.length double hyohen = sqrt(bunsan); hyohen sqrt(bunsan) sqrt bunsan System.out.printf("%.8f\n",hyohen) System.out.printf System.out System System.out "%.8f\n" hyohen input = in.nextLine() input in.nextLine() in.nextLine in cnt = Integer.parseInt(input) cnt Integer.parseInt(input) Integer.parseInt Integer input String[] arg arg
import java.util.Scanner;

import static java.lang.Math.pow;
import static java.lang.Math.sqrt;

class Main{
    
    public static void main(String[] arg){

        Scanner in = new Scanner(System.in);

        String input = in.nextLine();

        int cnt = Integer.parseInt(input);

        while(cnt != 0){
            double sum = 0.0;
            input = in.nextLine();
            String [] param_line = input.split(" ", 0);
            int [] points = new int[param_line.length];
            for(int i=0; i<points.length; i++){
                points[i] = Integer.parseInt(param_line[i]);
                sum += points[i];
            }

            double avg = sum/points.length;
            double tmp = 0;
            for(int i=0; i<points.length; i++)
                tmp += pow(points[i]-avg,2);

            double bunsan = tmp/points.length;
            double hyohen = sqrt(bunsan);

            System.out.printf("%.8f\n",hyohen);

            input = in.nextLine();
            cnt = Integer.parseInt(input);
        }
    }
}