import java.util.Scanner;

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

        Scanner scn = new Scanner(System.in);

        while(true){
            int count = scn.nextInt();

            if(count == 0) break;

            int [] array;
            array = new int[count];

            int sum = 0;
            Double ave = 0.0;
            Double ans = 0.0;
            Double answer = 0.0;


            for(int i = 0; i < count; i++){
                array[i] = scn.nextInt();
                sum += array[i];
            }

            ave = Double.valueOf(sum) / Double.valueOf(count);

            for(int i = 0; i < count; i++){
                ans += (array[i] - ave) * (array[i] - ave);
            }
            ans /= count;
            answer = Math.sqrt(ans);

            System.out.println(String.format("%.8f", answer));

        }
    }
}
 import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {

        Scanner scn = new Scanner(System.in);

        while(true){
            int count = scn.nextInt();

            if(count == 0) break;

            int [] array;
            array = new int[count];

            int sum = 0;
            Double ave = 0.0;
            Double ans = 0.0;
            Double answer = 0.0;


            for(int i = 0; i < count; i++){
                array[i] = scn.nextInt();
                sum += array[i];
            }

            ave = Double.valueOf(sum) / Double.valueOf(count);

            for(int i = 0; i < count; i++){
                ans += (array[i] - ave) * (array[i] - ave);
            }
            ans /= count;
            answer = Math.sqrt(ans);

            System.out.println(String.format("%.8f", answer));

        }
    }
} Main public static void main(String[] args) {

        Scanner scn = new Scanner(System.in);

        while(true){
            int count = scn.nextInt();

            if(count == 0) break;

            int [] array;
            array = new int[count];

            int sum = 0;
            Double ave = 0.0;
            Double ans = 0.0;
            Double answer = 0.0;


            for(int i = 0; i < count; i++){
                array[i] = scn.nextInt();
                sum += array[i];
            }

            ave = Double.valueOf(sum) / Double.valueOf(count);

            for(int i = 0; i < count; i++){
                ans += (array[i] - ave) * (array[i] - ave);
            }
            ans /= count;
            answer = Math.sqrt(ans);

            System.out.println(String.format("%.8f", answer));

        }
    } main {

        Scanner scn = new Scanner(System.in);

        while(true){
            int count = scn.nextInt();

            if(count == 0) break;

            int [] array;
            array = new int[count];

            int sum = 0;
            Double ave = 0.0;
            Double ans = 0.0;
            Double answer = 0.0;


            for(int i = 0; i < count; i++){
                array[i] = scn.nextInt();
                sum += array[i];
            }

            ave = Double.valueOf(sum) / Double.valueOf(count);

            for(int i = 0; i < count; i++){
                ans += (array[i] - ave) * (array[i] - ave);
            }
            ans /= count;
            answer = Math.sqrt(ans);

            System.out.println(String.format("%.8f", answer));

        }
    } Scanner scn = new Scanner(System.in); scn new Scanner(System.in) while(true){
            int count = scn.nextInt();

            if(count == 0) break;

            int [] array;
            array = new int[count];

            int sum = 0;
            Double ave = 0.0;
            Double ans = 0.0;
            Double answer = 0.0;


            for(int i = 0; i < count; i++){
                array[i] = scn.nextInt();
                sum += array[i];
            }

            ave = Double.valueOf(sum) / Double.valueOf(count);

            for(int i = 0; i < count; i++){
                ans += (array[i] - ave) * (array[i] - ave);
            }
            ans /= count;
            answer = Math.sqrt(ans);

            System.out.println(String.format("%.8f", answer));

        } true {
            int count = scn.nextInt();

            if(count == 0) break;

            int [] array;
            array = new int[count];

            int sum = 0;
            Double ave = 0.0;
            Double ans = 0.0;
            Double answer = 0.0;


            for(int i = 0; i < count; i++){
                array[i] = scn.nextInt();
                sum += array[i];
            }

            ave = Double.valueOf(sum) / Double.valueOf(count);

            for(int i = 0; i < count; i++){
                ans += (array[i] - ave) * (array[i] - ave);
            }
            ans /= count;
            answer = Math.sqrt(ans);

            System.out.println(String.format("%.8f", answer));

        } int count = scn.nextInt(); count scn.nextInt() scn.nextInt scn if(count == 0) break; count == 0 count 0 break; int [] array; array array = new int[count] array new int[count] count int sum = 0; sum 0 Double ave = 0.0; ave 0.0 Double ans = 0.0; ans 0.0 Double answer = 0.0; answer 0.0 for(int i = 0; i < count; i++){
                array[i] = scn.nextInt();
                sum += array[i];
            } int i = 0; int i = 0; i 0 i < count i count i++ i++ i {
                array[i] = scn.nextInt();
                sum += array[i];
            } {
                array[i] = scn.nextInt();
                sum += array[i];
            } array[i] = scn.nextInt() array[i] array i scn.nextInt() scn.nextInt scn sum += array[i] sum array[i] array i ave = Double.valueOf(sum) / Double.valueOf(count) ave Double.valueOf(sum) / Double.valueOf(count) Double.valueOf(sum) Double.valueOf Double sum Double.valueOf(count) Double.valueOf Double count for(int i = 0; i < count; i++){
                ans += (array[i] - ave) * (array[i] - ave);
            } int i = 0; int i = 0; i 0 i < count i count i++ i++ i {
                ans += (array[i] - ave) * (array[i] - ave);
            } {
                ans += (array[i] - ave) * (array[i] - ave);
            } ans += (array[i] - ave) * (array[i] - ave) ans (array[i] - ave) * (array[i] - ave) (array[i] - ave) array[i] array i ave (array[i] - ave) array[i] array i ave ans /= count ans count answer = Math.sqrt(ans) answer Math.sqrt(ans) Math.sqrt Math ans System.out.println(String.format("%.8f", answer)) System.out.println System.out System System.out String.format("%.8f", answer) String.format String "%.8f" answer String[] args args public class Main {
    public static void main(String[] args) {

        Scanner scn = new Scanner(System.in);

        while(true){
            int count = scn.nextInt();

            if(count == 0) break;

            int [] array;
            array = new int[count];

            int sum = 0;
            Double ave = 0.0;
            Double ans = 0.0;
            Double answer = 0.0;


            for(int i = 0; i < count; i++){
                array[i] = scn.nextInt();
                sum += array[i];
            }

            ave = Double.valueOf(sum) / Double.valueOf(count);

            for(int i = 0; i < count; i++){
                ans += (array[i] - ave) * (array[i] - ave);
            }
            ans /= count;
            answer = Math.sqrt(ans);

            System.out.println(String.format("%.8f", answer));

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

        Scanner scn = new Scanner(System.in);

        while(true){
            int count = scn.nextInt();

            if(count == 0) break;

            int [] array;
            array = new int[count];

            int sum = 0;
            Double ave = 0.0;
            Double ans = 0.0;
            Double answer = 0.0;


            for(int i = 0; i < count; i++){
                array[i] = scn.nextInt();
                sum += array[i];
            }

            ave = Double.valueOf(sum) / Double.valueOf(count);

            for(int i = 0; i < count; i++){
                ans += (array[i] - ave) * (array[i] - ave);
            }
            ans /= count;
            answer = Math.sqrt(ans);

            System.out.println(String.format("%.8f", answer));

        }
    }
} Main
import java.util.Scanner;

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

        Scanner scn = new Scanner(System.in);

        while(true){
            int count = scn.nextInt();

            if(count == 0) break;

            int [] array;
            array = new int[count];

            int sum = 0;
            Double ave = 0.0;
            Double ans = 0.0;
            Double answer = 0.0;


            for(int i = 0; i < count; i++){
                array[i] = scn.nextInt();
                sum += array[i];
            }

            ave = Double.valueOf(sum) / Double.valueOf(count);

            for(int i = 0; i < count; i++){
                ans += (array[i] - ave) * (array[i] - ave);
            }
            ans /= count;
            answer = Math.sqrt(ans);

            System.out.println(String.format("%.8f", answer));

        }
    }
}

