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

public class Main {

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

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			int count = Integer.parseInt(br.readLine());

			if (count == 0) {
				break;
			}

			String[] str = br.readLine().split(" ");
			double[] nums = new double[count];
			double sum = 0;
			for (int i = 0; i < count; i++) {
				nums[i] = Double.parseDouble(str[i]);
				sum += nums[i];
			}
			double avg = sum / count;
			double s = 0;

			for (int i = 0; i < count; i++) {
				s += Math.pow((nums[i] - avg),2);
			}
			System.out.println(Math.sqrt(s / count));
		}
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {

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

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			int count = Integer.parseInt(br.readLine());

			if (count == 0) {
				break;
			}

			String[] str = br.readLine().split(" ");
			double[] nums = new double[count];
			double sum = 0;
			for (int i = 0; i < count; i++) {
				nums[i] = Double.parseDouble(str[i]);
				sum += nums[i];
			}
			double avg = sum / count;
			double s = 0;

			for (int i = 0; i < count; i++) {
				s += Math.pow((nums[i] - avg),2);
			}
			System.out.println(Math.sqrt(s / count));
		}
	}
} Main public static void main(String[] args) throws IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			int count = Integer.parseInt(br.readLine());

			if (count == 0) {
				break;
			}

			String[] str = br.readLine().split(" ");
			double[] nums = new double[count];
			double sum = 0;
			for (int i = 0; i < count; i++) {
				nums[i] = Double.parseDouble(str[i]);
				sum += nums[i];
			}
			double avg = sum / count;
			double s = 0;

			for (int i = 0; i < count; i++) {
				s += Math.pow((nums[i] - avg),2);
			}
			System.out.println(Math.sqrt(s / count));
		}
	} main {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			int count = Integer.parseInt(br.readLine());

			if (count == 0) {
				break;
			}

			String[] str = br.readLine().split(" ");
			double[] nums = new double[count];
			double sum = 0;
			for (int i = 0; i < count; i++) {
				nums[i] = Double.parseDouble(str[i]);
				sum += nums[i];
			}
			double avg = sum / count;
			double s = 0;

			for (int i = 0; i < count; i++) {
				s += Math.pow((nums[i] - avg),2);
			}
			System.out.println(Math.sqrt(s / count));
		}
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) while (true) {
			int count = Integer.parseInt(br.readLine());

			if (count == 0) {
				break;
			}

			String[] str = br.readLine().split(" ");
			double[] nums = new double[count];
			double sum = 0;
			for (int i = 0; i < count; i++) {
				nums[i] = Double.parseDouble(str[i]);
				sum += nums[i];
			}
			double avg = sum / count;
			double s = 0;

			for (int i = 0; i < count; i++) {
				s += Math.pow((nums[i] - avg),2);
			}
			System.out.println(Math.sqrt(s / count));
		} true {
			int count = Integer.parseInt(br.readLine());

			if (count == 0) {
				break;
			}

			String[] str = br.readLine().split(" ");
			double[] nums = new double[count];
			double sum = 0;
			for (int i = 0; i < count; i++) {
				nums[i] = Double.parseDouble(str[i]);
				sum += nums[i];
			}
			double avg = sum / count;
			double s = 0;

			for (int i = 0; i < count; i++) {
				s += Math.pow((nums[i] - avg),2);
			}
			System.out.println(Math.sqrt(s / count));
		} int count = Integer.parseInt(br.readLine()); count Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br if (count == 0) {
				break;
			} count == 0 count 0 {
				break;
			} break; String[] str = br.readLine().split(" "); str br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " double[] nums = new double[count]; nums new double[count] count double sum = 0; sum 0 for (int i = 0; i < count; i++) {
				nums[i] = Double.parseDouble(str[i]);
				sum += nums[i];
			} int i = 0; int i = 0; i 0 i < count i count i++ i++ i {
				nums[i] = Double.parseDouble(str[i]);
				sum += nums[i];
			} {
				nums[i] = Double.parseDouble(str[i]);
				sum += nums[i];
			} nums[i] = Double.parseDouble(str[i]) nums[i] nums i Double.parseDouble(str[i]) Double.parseDouble Double str[i] str i sum += nums[i] sum nums[i] nums i double avg = sum / count; avg sum / count sum count double s = 0; s 0 for (int i = 0; i < count; i++) {
				s += Math.pow((nums[i] - avg),2);
			} int i = 0; int i = 0; i 0 i < count i count i++ i++ i {
				s += Math.pow((nums[i] - avg),2);
			} {
				s += Math.pow((nums[i] - avg),2);
			} s += Math.pow((nums[i] - avg),2) s Math.pow((nums[i] - avg),2) Math.pow Math (nums[i] - avg) nums[i] nums i avg 2 System.out.println(Math.sqrt(s / count)) System.out.println System.out System System.out Math.sqrt(s / count) Math.sqrt Math s / count s count String[] args args public class Main {

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

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			int count = Integer.parseInt(br.readLine());

			if (count == 0) {
				break;
			}

			String[] str = br.readLine().split(" ");
			double[] nums = new double[count];
			double sum = 0;
			for (int i = 0; i < count; i++) {
				nums[i] = Double.parseDouble(str[i]);
				sum += nums[i];
			}
			double avg = sum / count;
			double s = 0;

			for (int i = 0; i < count; i++) {
				s += Math.pow((nums[i] - avg),2);
			}
			System.out.println(Math.sqrt(s / count));
		}
	}
} public class Main {

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

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			int count = Integer.parseInt(br.readLine());

			if (count == 0) {
				break;
			}

			String[] str = br.readLine().split(" ");
			double[] nums = new double[count];
			double sum = 0;
			for (int i = 0; i < count; i++) {
				nums[i] = Double.parseDouble(str[i]);
				sum += nums[i];
			}
			double avg = sum / count;
			double s = 0;

			for (int i = 0; i < count; i++) {
				s += Math.pow((nums[i] - avg),2);
			}
			System.out.println(Math.sqrt(s / count));
		}
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

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

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while (true) {
			int count = Integer.parseInt(br.readLine());

			if (count == 0) {
				break;
			}

			String[] str = br.readLine().split(" ");
			double[] nums = new double[count];
			double sum = 0;
			for (int i = 0; i < count; i++) {
				nums[i] = Double.parseDouble(str[i]);
				sum += nums[i];
			}
			double avg = sum / count;
			double s = 0;

			for (int i = 0; i < count; i++) {
				s += Math.pow((nums[i] - avg),2);
			}
			System.out.println(Math.sqrt(s / count));
		}
	}
}