import java.io.IOException;
import java.util.Scanner;

class Main {

	public static void main(String[] args) throws IOException {

		Scanner scane = new Scanner(System.in);

		double n = scane.nextDouble();

		double[] nums = new double[1000];

		double totala = 0;

		double average = 0;

		double bunsan = 0;

		StringBuilder builder = new StringBuilder();

		while (n != 0) {

			for (int i = 0; i < n; i++) {
				nums[i] = scane.nextDouble();
				totala += nums[i];
			}

			average = totala / n;
			for (int i = 0; i < n; i++) {

				bunsan += Math.pow((nums[i] - average), 2);
			}

			builder.append(Math.sqrt(bunsan / n) + "\n");

			n = scane.nextDouble();

			totala = 0;
			bunsan = 0;

		}

		System.out.print(builder.toString());

	}

} import java.io.IOException; IOException java.io import java.util.Scanner; Scanner java.util class Main {

	public static void main(String[] args) throws IOException {

		Scanner scane = new Scanner(System.in);

		double n = scane.nextDouble();

		double[] nums = new double[1000];

		double totala = 0;

		double average = 0;

		double bunsan = 0;

		StringBuilder builder = new StringBuilder();

		while (n != 0) {

			for (int i = 0; i < n; i++) {
				nums[i] = scane.nextDouble();
				totala += nums[i];
			}

			average = totala / n;
			for (int i = 0; i < n; i++) {

				bunsan += Math.pow((nums[i] - average), 2);
			}

			builder.append(Math.sqrt(bunsan / n) + "\n");

			n = scane.nextDouble();

			totala = 0;
			bunsan = 0;

		}

		System.out.print(builder.toString());

	}

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

		Scanner scane = new Scanner(System.in);

		double n = scane.nextDouble();

		double[] nums = new double[1000];

		double totala = 0;

		double average = 0;

		double bunsan = 0;

		StringBuilder builder = new StringBuilder();

		while (n != 0) {

			for (int i = 0; i < n; i++) {
				nums[i] = scane.nextDouble();
				totala += nums[i];
			}

			average = totala / n;
			for (int i = 0; i < n; i++) {

				bunsan += Math.pow((nums[i] - average), 2);
			}

			builder.append(Math.sqrt(bunsan / n) + "\n");

			n = scane.nextDouble();

			totala = 0;
			bunsan = 0;

		}

		System.out.print(builder.toString());

	} main {

		Scanner scane = new Scanner(System.in);

		double n = scane.nextDouble();

		double[] nums = new double[1000];

		double totala = 0;

		double average = 0;

		double bunsan = 0;

		StringBuilder builder = new StringBuilder();

		while (n != 0) {

			for (int i = 0; i < n; i++) {
				nums[i] = scane.nextDouble();
				totala += nums[i];
			}

			average = totala / n;
			for (int i = 0; i < n; i++) {

				bunsan += Math.pow((nums[i] - average), 2);
			}

			builder.append(Math.sqrt(bunsan / n) + "\n");

			n = scane.nextDouble();

			totala = 0;
			bunsan = 0;

		}

		System.out.print(builder.toString());

	} Scanner scane = new Scanner(System.in); scane new Scanner(System.in) double n = scane.nextDouble(); n scane.nextDouble() scane.nextDouble scane double[] nums = new double[1000]; nums new double[1000] 1000 double totala = 0; totala 0 double average = 0; average 0 double bunsan = 0; bunsan 0 StringBuilder builder = new StringBuilder(); builder new StringBuilder() while (n != 0) {

			for (int i = 0; i < n; i++) {
				nums[i] = scane.nextDouble();
				totala += nums[i];
			}

			average = totala / n;
			for (int i = 0; i < n; i++) {

				bunsan += Math.pow((nums[i] - average), 2);
			}

			builder.append(Math.sqrt(bunsan / n) + "\n");

			n = scane.nextDouble();

			totala = 0;
			bunsan = 0;

		} n != 0 n 0 {

			for (int i = 0; i < n; i++) {
				nums[i] = scane.nextDouble();
				totala += nums[i];
			}

			average = totala / n;
			for (int i = 0; i < n; i++) {

				bunsan += Math.pow((nums[i] - average), 2);
			}

			builder.append(Math.sqrt(bunsan / n) + "\n");

			n = scane.nextDouble();

			totala = 0;
			bunsan = 0;

		} for (int i = 0; i < n; i++) {
				nums[i] = scane.nextDouble();
				totala += nums[i];
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				nums[i] = scane.nextDouble();
				totala += nums[i];
			} {
				nums[i] = scane.nextDouble();
				totala += nums[i];
			} nums[i] = scane.nextDouble() nums[i] nums i scane.nextDouble() scane.nextDouble scane totala += nums[i] totala nums[i] nums i average = totala / n average totala / n totala n for (int i = 0; i < n; i++) {

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

				bunsan += Math.pow((nums[i] - average), 2);
			} {

				bunsan += Math.pow((nums[i] - average), 2);
			} bunsan += Math.pow((nums[i] - average), 2) bunsan Math.pow((nums[i] - average), 2) Math.pow Math (nums[i] - average) nums[i] nums i average 2 builder.append(Math.sqrt(bunsan / n) + "\n") builder.append builder Math.sqrt(bunsan / n) + "\n" Math.sqrt(bunsan / n) Math.sqrt Math bunsan / n bunsan n "\n" n = scane.nextDouble() n scane.nextDouble() scane.nextDouble scane totala = 0 totala 0 bunsan = 0 bunsan 0 System.out.print(builder.toString()) System.out.print System.out System System.out builder.toString() builder.toString builder String[] args args
import java.io.IOException;
import java.util.Scanner;

class Main {

	public static void main(String[] args) throws IOException {

		Scanner scane = new Scanner(System.in);

		double n = scane.nextDouble();

		double[] nums = new double[1000];

		double totala = 0;

		double average = 0;

		double bunsan = 0;

		StringBuilder builder = new StringBuilder();

		while (n != 0) {

			for (int i = 0; i < n; i++) {
				nums[i] = scane.nextDouble();
				totala += nums[i];
			}

			average = totala / n;
			for (int i = 0; i < n; i++) {

				bunsan += Math.pow((nums[i] - average), 2);
			}

			builder.append(Math.sqrt(bunsan / n) + "\n");

			n = scane.nextDouble();

			totala = 0;
			bunsan = 0;

		}

		System.out.print(builder.toString());

	}

}