import java.io.IOException;
import java.io.InputStreamReader;
import java.io.BufferedReader;

public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line;

        while(!((line = br.readLine()).equals("0"))){
            int n = Integer.parseInt(line);
            String[] input = br.readLine().split(" ");
            int[] data = new int[n];

            double sum = 0;
            double squaresum = 0;
            double average;

            for(int i = 0; i < n; i++){
                data[i] = Integer.parseInt(input[i]);
                sum += data[i];
            }

            average = sum/n;

            for(int i = 0; i < n; i++){
                squaresum += Math.pow(data[i]-average , 2);
            }

            double variance = squaresum / n;

            System.out.println(Math.sqrt(variance));
        }
    }
} import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.BufferedReader; BufferedReader java.io public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line;

        while(!((line = br.readLine()).equals("0"))){
            int n = Integer.parseInt(line);
            String[] input = br.readLine().split(" ");
            int[] data = new int[n];

            double sum = 0;
            double squaresum = 0;
            double average;

            for(int i = 0; i < n; i++){
                data[i] = Integer.parseInt(input[i]);
                sum += data[i];
            }

            average = sum/n;

            for(int i = 0; i < n; i++){
                squaresum += Math.pow(data[i]-average , 2);
            }

            double variance = squaresum / n;

            System.out.println(Math.sqrt(variance));
        }
    }
} Main public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line;

        while(!((line = br.readLine()).equals("0"))){
            int n = Integer.parseInt(line);
            String[] input = br.readLine().split(" ");
            int[] data = new int[n];

            double sum = 0;
            double squaresum = 0;
            double average;

            for(int i = 0; i < n; i++){
                data[i] = Integer.parseInt(input[i]);
                sum += data[i];
            }

            average = sum/n;

            for(int i = 0; i < n; i++){
                squaresum += Math.pow(data[i]-average , 2);
            }

            double variance = squaresum / n;

            System.out.println(Math.sqrt(variance));
        }
    } main {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line;

        while(!((line = br.readLine()).equals("0"))){
            int n = Integer.parseInt(line);
            String[] input = br.readLine().split(" ");
            int[] data = new int[n];

            double sum = 0;
            double squaresum = 0;
            double average;

            for(int i = 0; i < n; i++){
                data[i] = Integer.parseInt(input[i]);
                sum += data[i];
            }

            average = sum/n;

            for(int i = 0; i < n; i++){
                squaresum += Math.pow(data[i]-average , 2);
            }

            double variance = squaresum / n;

            System.out.println(Math.sqrt(variance));
        }
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) String line; line while(!((line = br.readLine()).equals("0"))){
            int n = Integer.parseInt(line);
            String[] input = br.readLine().split(" ");
            int[] data = new int[n];

            double sum = 0;
            double squaresum = 0;
            double average;

            for(int i = 0; i < n; i++){
                data[i] = Integer.parseInt(input[i]);
                sum += data[i];
            }

            average = sum/n;

            for(int i = 0; i < n; i++){
                squaresum += Math.pow(data[i]-average , 2);
            }

            double variance = squaresum / n;

            System.out.println(Math.sqrt(variance));
        } !((line = br.readLine()).equals("0")) ((line = br.readLine()).equals("0")) (line = br.readLine()).equals (line = br.readLine()) line br.readLine() br.readLine br "0" {
            int n = Integer.parseInt(line);
            String[] input = br.readLine().split(" ");
            int[] data = new int[n];

            double sum = 0;
            double squaresum = 0;
            double average;

            for(int i = 0; i < n; i++){
                data[i] = Integer.parseInt(input[i]);
                sum += data[i];
            }

            average = sum/n;

            for(int i = 0; i < n; i++){
                squaresum += Math.pow(data[i]-average , 2);
            }

            double variance = squaresum / n;

            System.out.println(Math.sqrt(variance));
        } int n = Integer.parseInt(line); n Integer.parseInt(line) Integer.parseInt Integer line String[] input = br.readLine().split(" "); input br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " int[] data = new int[n]; data new int[n] n double sum = 0; sum 0 double squaresum = 0; squaresum 0 double average; average for(int i = 0; i < n; i++){
                data[i] = Integer.parseInt(input[i]);
                sum += data[i];
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                data[i] = Integer.parseInt(input[i]);
                sum += data[i];
            } {
                data[i] = Integer.parseInt(input[i]);
                sum += data[i];
            } data[i] = Integer.parseInt(input[i]) data[i] data i Integer.parseInt(input[i]) Integer.parseInt Integer input[i] input i sum += data[i] sum data[i] data i average = sum/n average sum/n sum n for(int i = 0; i < n; i++){
                squaresum += Math.pow(data[i]-average , 2);
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                squaresum += Math.pow(data[i]-average , 2);
            } {
                squaresum += Math.pow(data[i]-average , 2);
            } squaresum += Math.pow(data[i]-average , 2) squaresum Math.pow(data[i]-average , 2) Math.pow Math data[i]-average data[i] data i average 2 double variance = squaresum / n; variance squaresum / n squaresum n System.out.println(Math.sqrt(variance)) System.out.println System.out System System.out Math.sqrt(variance) Math.sqrt Math variance String[] args args public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line;

        while(!((line = br.readLine()).equals("0"))){
            int n = Integer.parseInt(line);
            String[] input = br.readLine().split(" ");
            int[] data = new int[n];

            double sum = 0;
            double squaresum = 0;
            double average;

            for(int i = 0; i < n; i++){
                data[i] = Integer.parseInt(input[i]);
                sum += data[i];
            }

            average = sum/n;

            for(int i = 0; i < n; i++){
                squaresum += Math.pow(data[i]-average , 2);
            }

            double variance = squaresum / n;

            System.out.println(Math.sqrt(variance));
        }
    }
} public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line;

        while(!((line = br.readLine()).equals("0"))){
            int n = Integer.parseInt(line);
            String[] input = br.readLine().split(" ");
            int[] data = new int[n];

            double sum = 0;
            double squaresum = 0;
            double average;

            for(int i = 0; i < n; i++){
                data[i] = Integer.parseInt(input[i]);
                sum += data[i];
            }

            average = sum/n;

            for(int i = 0; i < n; i++){
                squaresum += Math.pow(data[i]-average , 2);
            }

            double variance = squaresum / n;

            System.out.println(Math.sqrt(variance));
        }
    }
} Main
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.BufferedReader;

public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line;

        while(!((line = br.readLine()).equals("0"))){
            int n = Integer.parseInt(line);
            String[] input = br.readLine().split(" ");
            int[] data = new int[n];

            double sum = 0;
            double squaresum = 0;
            double average;

            for(int i = 0; i < n; i++){
                data[i] = Integer.parseInt(input[i]);
                sum += data[i];
            }

            average = sum/n;

            for(int i = 0; i < n; i++){
                squaresum += Math.pow(data[i]-average , 2);
            }

            double variance = squaresum / n;

            System.out.println(Math.sqrt(variance));
        }
    }
}