import java.util.Scanner;

public class Main {

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

        for (int n = sc.nextInt(); n != 0; n = sc.nextInt()) {
        	int[] data = new int[n];
        	int sum = 0;
        	for (int i = 0; i < n; i++) {
        		data[i] = sc.nextInt();
        		sum += data[i];
        	}
        	double average = (double)sum / n;

        	double sd = 0.0;
        	for (int i = 0; i < n; i++) {
        		sd += Math.pow(data[i] - average, 2);
        	}
        	sd /= n;

        	System.out.println(String.format("%.4f", Math.sqrt(sd)));
        }
         
        sc.close();
	}
} import java.util.Scanner; Scanner java.util public class Main {

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

        for (int n = sc.nextInt(); n != 0; n = sc.nextInt()) {
        	int[] data = new int[n];
        	int sum = 0;
        	for (int i = 0; i < n; i++) {
        		data[i] = sc.nextInt();
        		sum += data[i];
        	}
        	double average = (double)sum / n;

        	double sd = 0.0;
        	for (int i = 0; i < n; i++) {
        		sd += Math.pow(data[i] - average, 2);
        	}
        	sd /= n;

        	System.out.println(String.format("%.4f", Math.sqrt(sd)));
        }
         
        sc.close();
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in); 

        for (int n = sc.nextInt(); n != 0; n = sc.nextInt()) {
        	int[] data = new int[n];
        	int sum = 0;
        	for (int i = 0; i < n; i++) {
        		data[i] = sc.nextInt();
        		sum += data[i];
        	}
        	double average = (double)sum / n;

        	double sd = 0.0;
        	for (int i = 0; i < n; i++) {
        		sd += Math.pow(data[i] - average, 2);
        	}
        	sd /= n;

        	System.out.println(String.format("%.4f", Math.sqrt(sd)));
        }
         
        sc.close();
	} main {
		Scanner sc = new Scanner(System.in); 

        for (int n = sc.nextInt(); n != 0; n = sc.nextInt()) {
        	int[] data = new int[n];
        	int sum = 0;
        	for (int i = 0; i < n; i++) {
        		data[i] = sc.nextInt();
        		sum += data[i];
        	}
        	double average = (double)sum / n;

        	double sd = 0.0;
        	for (int i = 0; i < n; i++) {
        		sd += Math.pow(data[i] - average, 2);
        	}
        	sd /= n;

        	System.out.println(String.format("%.4f", Math.sqrt(sd)));
        }
         
        sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) for (int n = sc.nextInt(); n != 0; n = sc.nextInt()) {
        	int[] data = new int[n];
        	int sum = 0;
        	for (int i = 0; i < n; i++) {
        		data[i] = sc.nextInt();
        		sum += data[i];
        	}
        	double average = (double)sum / n;

        	double sd = 0.0;
        	for (int i = 0; i < n; i++) {
        		sd += Math.pow(data[i] - average, 2);
        	}
        	sd /= n;

        	System.out.println(String.format("%.4f", Math.sqrt(sd)));
        } int n = sc.nextInt(); int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc n != 0 n 0 n = sc.nextInt() n = sc.nextInt() n sc.nextInt() sc.nextInt sc {
        	int[] data = new int[n];
        	int sum = 0;
        	for (int i = 0; i < n; i++) {
        		data[i] = sc.nextInt();
        		sum += data[i];
        	}
        	double average = (double)sum / n;

        	double sd = 0.0;
        	for (int i = 0; i < n; i++) {
        		sd += Math.pow(data[i] - average, 2);
        	}
        	sd /= n;

        	System.out.println(String.format("%.4f", Math.sqrt(sd)));
        } {
        	int[] data = new int[n];
        	int sum = 0;
        	for (int i = 0; i < n; i++) {
        		data[i] = sc.nextInt();
        		sum += data[i];
        	}
        	double average = (double)sum / n;

        	double sd = 0.0;
        	for (int i = 0; i < n; i++) {
        		sd += Math.pow(data[i] - average, 2);
        	}
        	sd /= n;

        	System.out.println(String.format("%.4f", Math.sqrt(sd)));
        } int[] data = new int[n]; data new int[n] n int sum = 0; sum 0 for (int i = 0; i < n; i++) {
        		data[i] = sc.nextInt();
        		sum += data[i];
        	} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
        		data[i] = sc.nextInt();
        		sum += data[i];
        	} {
        		data[i] = sc.nextInt();
        		sum += data[i];
        	} data[i] = sc.nextInt() data[i] data i sc.nextInt() sc.nextInt sc sum += data[i] sum data[i] data i double average = (double)sum / n; average (double)sum / n (double)sum n double sd = 0.0; sd 0.0 for (int i = 0; i < n; i++) {
        		sd += Math.pow(data[i] - average, 2);
        	} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
        		sd += Math.pow(data[i] - average, 2);
        	} {
        		sd += Math.pow(data[i] - average, 2);
        	} sd += Math.pow(data[i] - average, 2) sd Math.pow(data[i] - average, 2) Math.pow Math data[i] - average data[i] data i average 2 sd /= n sd n System.out.println(String.format("%.4f", Math.sqrt(sd))) System.out.println System.out System System.out String.format("%.4f", Math.sqrt(sd)) String.format String "%.4f" Math.sqrt(sd) Math.sqrt Math sd sc.close() sc.close sc String[] args args public class Main {

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

        for (int n = sc.nextInt(); n != 0; n = sc.nextInt()) {
        	int[] data = new int[n];
        	int sum = 0;
        	for (int i = 0; i < n; i++) {
        		data[i] = sc.nextInt();
        		sum += data[i];
        	}
        	double average = (double)sum / n;

        	double sd = 0.0;
        	for (int i = 0; i < n; i++) {
        		sd += Math.pow(data[i] - average, 2);
        	}
        	sd /= n;

        	System.out.println(String.format("%.4f", Math.sqrt(sd)));
        }
         
        sc.close();
	}
} public class Main {

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

        for (int n = sc.nextInt(); n != 0; n = sc.nextInt()) {
        	int[] data = new int[n];
        	int sum = 0;
        	for (int i = 0; i < n; i++) {
        		data[i] = sc.nextInt();
        		sum += data[i];
        	}
        	double average = (double)sum / n;

        	double sd = 0.0;
        	for (int i = 0; i < n; i++) {
        		sd += Math.pow(data[i] - average, 2);
        	}
        	sd /= n;

        	System.out.println(String.format("%.4f", Math.sqrt(sd)));
        }
         
        sc.close();
	}
} Main
import java.util.Scanner;

public class Main {

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

        for (int n = sc.nextInt(); n != 0; n = sc.nextInt()) {
        	int[] data = new int[n];
        	int sum = 0;
        	for (int i = 0; i < n; i++) {
        		data[i] = sc.nextInt();
        		sum += data[i];
        	}
        	double average = (double)sum / n;

        	double sd = 0.0;
        	for (int i = 0; i < n; i++) {
        		sd += Math.pow(data[i] - average, 2);
        	}
        	sd /= n;

        	System.out.println(String.format("%.4f", Math.sqrt(sd)));
        }
         
        sc.close();
	}
}