import java.util.Scanner;
import java.util.ArrayList;

public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		ArrayList<Double> data = new ArrayList<>();
		while (true) {
			int n = sc.nextInt();
			if (n == 0) {
				break;
			}
			int sum = 0;
			int[] s = new int[n];
			double m;
			double a;
			double sigma = 0;
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				sum += s[i];
			}
			m = (double) sum / n;
			for (int i = 0; i < n; i++) {
				sigma += Math.pow(s[i] - m, 2) / n;
			}
			a = Math.sqrt(sigma);
			data.add(a);
		}
		for (int i = 0; i < data.size(); i++) {
			System.out.printf("%f%n", data.get(i));
		}
		sc.close();
	}
} import java.util.Scanner; Scanner java.util import java.util.ArrayList; ArrayList java.util public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		ArrayList<Double> data = new ArrayList<>();
		while (true) {
			int n = sc.nextInt();
			if (n == 0) {
				break;
			}
			int sum = 0;
			int[] s = new int[n];
			double m;
			double a;
			double sigma = 0;
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				sum += s[i];
			}
			m = (double) sum / n;
			for (int i = 0; i < n; i++) {
				sigma += Math.pow(s[i] - m, 2) / n;
			}
			a = Math.sqrt(sigma);
			data.add(a);
		}
		for (int i = 0; i < data.size(); i++) {
			System.out.printf("%f%n", data.get(i));
		}
		sc.close();
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		ArrayList<Double> data = new ArrayList<>();
		while (true) {
			int n = sc.nextInt();
			if (n == 0) {
				break;
			}
			int sum = 0;
			int[] s = new int[n];
			double m;
			double a;
			double sigma = 0;
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				sum += s[i];
			}
			m = (double) sum / n;
			for (int i = 0; i < n; i++) {
				sigma += Math.pow(s[i] - m, 2) / n;
			}
			a = Math.sqrt(sigma);
			data.add(a);
		}
		for (int i = 0; i < data.size(); i++) {
			System.out.printf("%f%n", data.get(i));
		}
		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);
		ArrayList<Double> data = new ArrayList<>();
		while (true) {
			int n = sc.nextInt();
			if (n == 0) {
				break;
			}
			int sum = 0;
			int[] s = new int[n];
			double m;
			double a;
			double sigma = 0;
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				sum += s[i];
			}
			m = (double) sum / n;
			for (int i = 0; i < n; i++) {
				sigma += Math.pow(s[i] - m, 2) / n;
			}
			a = Math.sqrt(sigma);
			data.add(a);
		}
		for (int i = 0; i < data.size(); i++) {
			System.out.printf("%f%n", data.get(i));
		}
		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) ArrayList<Double> data = new ArrayList<>(); data new ArrayList<>() while (true) {
			int n = sc.nextInt();
			if (n == 0) {
				break;
			}
			int sum = 0;
			int[] s = new int[n];
			double m;
			double a;
			double sigma = 0;
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				sum += s[i];
			}
			m = (double) sum / n;
			for (int i = 0; i < n; i++) {
				sigma += Math.pow(s[i] - m, 2) / n;
			}
			a = Math.sqrt(sigma);
			data.add(a);
		} true {
			int n = sc.nextInt();
			if (n == 0) {
				break;
			}
			int sum = 0;
			int[] s = new int[n];
			double m;
			double a;
			double sigma = 0;
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				sum += s[i];
			}
			m = (double) sum / n;
			for (int i = 0; i < n; i++) {
				sigma += Math.pow(s[i] - m, 2) / n;
			}
			a = Math.sqrt(sigma);
			data.add(a);
		} int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if (n == 0) {
				break;
			} n == 0 n 0 {
				break;
			} break; int sum = 0; sum 0 int[] s = new int[n]; s new int[n] n double m; m double a; a double sigma = 0; sigma 0 for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				sum += s[i];
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				s[i] = sc.nextInt();
				sum += s[i];
			} {
				s[i] = sc.nextInt();
				sum += s[i];
			} s[i] = sc.nextInt() s[i] s i sc.nextInt() sc.nextInt sc sum += s[i] sum s[i] s i m = (double) sum / n m (double) sum / n (double) sum n for (int i = 0; i < n; i++) {
				sigma += Math.pow(s[i] - m, 2) / n;
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				sigma += Math.pow(s[i] - m, 2) / n;
			} {
				sigma += Math.pow(s[i] - m, 2) / n;
			} sigma += Math.pow(s[i] - m, 2) / n sigma Math.pow(s[i] - m, 2) / n Math.pow(s[i] - m, 2) Math.pow Math s[i] - m s[i] s i m 2 n a = Math.sqrt(sigma) a Math.sqrt(sigma) Math.sqrt Math sigma data.add(a) data.add data a for (int i = 0; i < data.size(); i++) {
			System.out.printf("%f%n", data.get(i));
		} int i = 0; int i = 0; i 0 i < data.size() i data.size() data.size data i++ i++ i {
			System.out.printf("%f%n", data.get(i));
		} {
			System.out.printf("%f%n", data.get(i));
		} System.out.printf("%f%n", data.get(i)) System.out.printf System.out System System.out "%f%n" data.get(i) data.get data i sc.close() sc.close sc String[] args args public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		ArrayList<Double> data = new ArrayList<>();
		while (true) {
			int n = sc.nextInt();
			if (n == 0) {
				break;
			}
			int sum = 0;
			int[] s = new int[n];
			double m;
			double a;
			double sigma = 0;
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				sum += s[i];
			}
			m = (double) sum / n;
			for (int i = 0; i < n; i++) {
				sigma += Math.pow(s[i] - m, 2) / n;
			}
			a = Math.sqrt(sigma);
			data.add(a);
		}
		for (int i = 0; i < data.size(); i++) {
			System.out.printf("%f%n", data.get(i));
		}
		sc.close();
	}
} public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		ArrayList<Double> data = new ArrayList<>();
		while (true) {
			int n = sc.nextInt();
			if (n == 0) {
				break;
			}
			int sum = 0;
			int[] s = new int[n];
			double m;
			double a;
			double sigma = 0;
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				sum += s[i];
			}
			m = (double) sum / n;
			for (int i = 0; i < n; i++) {
				sigma += Math.pow(s[i] - m, 2) / n;
			}
			a = Math.sqrt(sigma);
			data.add(a);
		}
		for (int i = 0; i < data.size(); i++) {
			System.out.printf("%f%n", data.get(i));
		}
		sc.close();
	}
} Main
import java.util.Scanner;
import java.util.ArrayList;

public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		ArrayList<Double> data = new ArrayList<>();
		while (true) {
			int n = sc.nextInt();
			if (n == 0) {
				break;
			}
			int sum = 0;
			int[] s = new int[n];
			double m;
			double a;
			double sigma = 0;
			for (int i = 0; i < n; i++) {
				s[i] = sc.nextInt();
				sum += s[i];
			}
			m = (double) sum / n;
			for (int i = 0; i < n; i++) {
				sigma += Math.pow(s[i] - m, 2) / n;
			}
			a = Math.sqrt(sigma);
			data.add(a);
		}
		for (int i = 0; i < data.size(); i++) {
			System.out.printf("%f%n", data.get(i));
		}
		sc.close();
	}
}
