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

public class Main {

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

		while (true) {

			String first_line = input.readLine();

			// ????????°??¨?????°
			int student_num = Integer.parseInt(first_line);

			if (student_num == 0) {

				break;

			}

			// ????????\?????¨?????°
			String secound_lines = input.readLine();

			String[] score_arrays = secound_lines.split(" ");

			// ?????°???????¨???¨?????°
			double score_sum = 0;

			//n???????????????????????????????????°?????????
			for (int score_spot = 0; score_spot < score_arrays.length; score_spot++) {

				int score = Integer.parseInt(score_arrays[score_spot]);

				score_sum += score;

			}

			//???????????????
			double average = score_sum / student_num;

			//??°???a???2???
			double sequence_a_square = 0;

			//??°???a???2??????????????????
			for (int sequence_spot = 0; sequence_spot < score_arrays.length; sequence_spot++) {

				double score = Double.parseDouble(score_arrays[sequence_spot]);


				sequence_a_square += Math.pow(score - average, 2);

			}

			double distributed_a_square = sequence_a_square / student_num;

			//??°???a????????????
			double square_a = Math.sqrt(distributed_a_square);

			System.out.println(square_a);
		}

	}

} 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 input = new BufferedReader(new InputStreamReader(System.in));

		while (true) {

			String first_line = input.readLine();

			// ????????°??¨?????°
			int student_num = Integer.parseInt(first_line);

			if (student_num == 0) {

				break;

			}

			// ????????\?????¨?????°
			String secound_lines = input.readLine();

			String[] score_arrays = secound_lines.split(" ");

			// ?????°???????¨???¨?????°
			double score_sum = 0;

			//n???????????????????????????????????°?????????
			for (int score_spot = 0; score_spot < score_arrays.length; score_spot++) {

				int score = Integer.parseInt(score_arrays[score_spot]);

				score_sum += score;

			}

			//???????????????
			double average = score_sum / student_num;

			//??°???a???2???
			double sequence_a_square = 0;

			//??°???a???2??????????????????
			for (int sequence_spot = 0; sequence_spot < score_arrays.length; sequence_spot++) {

				double score = Double.parseDouble(score_arrays[sequence_spot]);


				sequence_a_square += Math.pow(score - average, 2);

			}

			double distributed_a_square = sequence_a_square / student_num;

			//??°???a????????????
			double square_a = Math.sqrt(distributed_a_square);

			System.out.println(square_a);
		}

	}

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

		while (true) {

			String first_line = input.readLine();

			// ????????°??¨?????°
			int student_num = Integer.parseInt(first_line);

			if (student_num == 0) {

				break;

			}

			// ????????\?????¨?????°
			String secound_lines = input.readLine();

			String[] score_arrays = secound_lines.split(" ");

			// ?????°???????¨???¨?????°
			double score_sum = 0;

			//n???????????????????????????????????°?????????
			for (int score_spot = 0; score_spot < score_arrays.length; score_spot++) {

				int score = Integer.parseInt(score_arrays[score_spot]);

				score_sum += score;

			}

			//???????????????
			double average = score_sum / student_num;

			//??°???a???2???
			double sequence_a_square = 0;

			//??°???a???2??????????????????
			for (int sequence_spot = 0; sequence_spot < score_arrays.length; sequence_spot++) {

				double score = Double.parseDouble(score_arrays[sequence_spot]);


				sequence_a_square += Math.pow(score - average, 2);

			}

			double distributed_a_square = sequence_a_square / student_num;

			//??°???a????????????
			double square_a = Math.sqrt(distributed_a_square);

			System.out.println(square_a);
		}

	} main {
		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));

		while (true) {

			String first_line = input.readLine();

			// ????????°??¨?????°
			int student_num = Integer.parseInt(first_line);

			if (student_num == 0) {

				break;

			}

			// ????????\?????¨?????°
			String secound_lines = input.readLine();

			String[] score_arrays = secound_lines.split(" ");

			// ?????°???????¨???¨?????°
			double score_sum = 0;

			//n???????????????????????????????????°?????????
			for (int score_spot = 0; score_spot < score_arrays.length; score_spot++) {

				int score = Integer.parseInt(score_arrays[score_spot]);

				score_sum += score;

			}

			//???????????????
			double average = score_sum / student_num;

			//??°???a???2???
			double sequence_a_square = 0;

			//??°???a???2??????????????????
			for (int sequence_spot = 0; sequence_spot < score_arrays.length; sequence_spot++) {

				double score = Double.parseDouble(score_arrays[sequence_spot]);


				sequence_a_square += Math.pow(score - average, 2);

			}

			double distributed_a_square = sequence_a_square / student_num;

			//??°???a????????????
			double square_a = Math.sqrt(distributed_a_square);

			System.out.println(square_a);
		}

	} BufferedReader input = new BufferedReader(new InputStreamReader(System.in)); input new BufferedReader(new InputStreamReader(System.in)) while (true) {

			String first_line = input.readLine();

			// ????????°??¨?????°
			int student_num = Integer.parseInt(first_line);

			if (student_num == 0) {

				break;

			}

			// ????????\?????¨?????°
			String secound_lines = input.readLine();

			String[] score_arrays = secound_lines.split(" ");

			// ?????°???????¨???¨?????°
			double score_sum = 0;

			//n???????????????????????????????????°?????????
			for (int score_spot = 0; score_spot < score_arrays.length; score_spot++) {

				int score = Integer.parseInt(score_arrays[score_spot]);

				score_sum += score;

			}

			//???????????????
			double average = score_sum / student_num;

			//??°???a???2???
			double sequence_a_square = 0;

			//??°???a???2??????????????????
			for (int sequence_spot = 0; sequence_spot < score_arrays.length; sequence_spot++) {

				double score = Double.parseDouble(score_arrays[sequence_spot]);


				sequence_a_square += Math.pow(score - average, 2);

			}

			double distributed_a_square = sequence_a_square / student_num;

			//??°???a????????????
			double square_a = Math.sqrt(distributed_a_square);

			System.out.println(square_a);
		} true {

			String first_line = input.readLine();

			// ????????°??¨?????°
			int student_num = Integer.parseInt(first_line);

			if (student_num == 0) {

				break;

			}

			// ????????\?????¨?????°
			String secound_lines = input.readLine();

			String[] score_arrays = secound_lines.split(" ");

			// ?????°???????¨???¨?????°
			double score_sum = 0;

			//n???????????????????????????????????°?????????
			for (int score_spot = 0; score_spot < score_arrays.length; score_spot++) {

				int score = Integer.parseInt(score_arrays[score_spot]);

				score_sum += score;

			}

			//???????????????
			double average = score_sum / student_num;

			//??°???a???2???
			double sequence_a_square = 0;

			//??°???a???2??????????????????
			for (int sequence_spot = 0; sequence_spot < score_arrays.length; sequence_spot++) {

				double score = Double.parseDouble(score_arrays[sequence_spot]);


				sequence_a_square += Math.pow(score - average, 2);

			}

			double distributed_a_square = sequence_a_square / student_num;

			//??°???a????????????
			double square_a = Math.sqrt(distributed_a_square);

			System.out.println(square_a);
		} String first_line = input.readLine(); first_line input.readLine() input.readLine input int student_num = Integer.parseInt(first_line); student_num Integer.parseInt(first_line) Integer.parseInt Integer first_line if (student_num == 0) {

				break;

			} student_num == 0 student_num 0 {

				break;

			} break; String secound_lines = input.readLine(); secound_lines input.readLine() input.readLine input String[] score_arrays = secound_lines.split(" "); score_arrays secound_lines.split(" ") secound_lines.split secound_lines " " double score_sum = 0; score_sum 0 for (int score_spot = 0; score_spot < score_arrays.length; score_spot++) {

				int score = Integer.parseInt(score_arrays[score_spot]);

				score_sum += score;

			} int score_spot = 0; int score_spot = 0; score_spot 0 score_spot < score_arrays.length score_spot score_arrays.length score_arrays score_arrays.length score_spot++ score_spot++ score_spot {

				int score = Integer.parseInt(score_arrays[score_spot]);

				score_sum += score;

			} {

				int score = Integer.parseInt(score_arrays[score_spot]);

				score_sum += score;

			} int score = Integer.parseInt(score_arrays[score_spot]); score Integer.parseInt(score_arrays[score_spot]) Integer.parseInt Integer score_arrays[score_spot] score_arrays score_spot score_sum += score score_sum score double average = score_sum / student_num; average score_sum / student_num score_sum student_num double sequence_a_square = 0; sequence_a_square 0 for (int sequence_spot = 0; sequence_spot < score_arrays.length; sequence_spot++) {

				double score = Double.parseDouble(score_arrays[sequence_spot]);


				sequence_a_square += Math.pow(score - average, 2);

			} int sequence_spot = 0; int sequence_spot = 0; sequence_spot 0 sequence_spot < score_arrays.length sequence_spot score_arrays.length score_arrays score_arrays.length sequence_spot++ sequence_spot++ sequence_spot {

				double score = Double.parseDouble(score_arrays[sequence_spot]);


				sequence_a_square += Math.pow(score - average, 2);

			} {

				double score = Double.parseDouble(score_arrays[sequence_spot]);


				sequence_a_square += Math.pow(score - average, 2);

			} double score = Double.parseDouble(score_arrays[sequence_spot]); score Double.parseDouble(score_arrays[sequence_spot]) Double.parseDouble Double score_arrays[sequence_spot] score_arrays sequence_spot sequence_a_square += Math.pow(score - average, 2) sequence_a_square Math.pow(score - average, 2) Math.pow Math score - average score average 2 double distributed_a_square = sequence_a_square / student_num; distributed_a_square sequence_a_square / student_num sequence_a_square student_num double square_a = Math.sqrt(distributed_a_square); square_a Math.sqrt(distributed_a_square) Math.sqrt Math distributed_a_square System.out.println(square_a) System.out.println System.out System System.out square_a String[] args args public class Main {

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

		while (true) {

			String first_line = input.readLine();

			// ????????°??¨?????°
			int student_num = Integer.parseInt(first_line);

			if (student_num == 0) {

				break;

			}

			// ????????\?????¨?????°
			String secound_lines = input.readLine();

			String[] score_arrays = secound_lines.split(" ");

			// ?????°???????¨???¨?????°
			double score_sum = 0;

			//n???????????????????????????????????°?????????
			for (int score_spot = 0; score_spot < score_arrays.length; score_spot++) {

				int score = Integer.parseInt(score_arrays[score_spot]);

				score_sum += score;

			}

			//???????????????
			double average = score_sum / student_num;

			//??°???a???2???
			double sequence_a_square = 0;

			//??°???a???2??????????????????
			for (int sequence_spot = 0; sequence_spot < score_arrays.length; sequence_spot++) {

				double score = Double.parseDouble(score_arrays[sequence_spot]);


				sequence_a_square += Math.pow(score - average, 2);

			}

			double distributed_a_square = sequence_a_square / student_num;

			//??°???a????????????
			double square_a = Math.sqrt(distributed_a_square);

			System.out.println(square_a);
		}

	}

} public class Main {

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

		while (true) {

			String first_line = input.readLine();

			// ????????°??¨?????°
			int student_num = Integer.parseInt(first_line);

			if (student_num == 0) {

				break;

			}

			// ????????\?????¨?????°
			String secound_lines = input.readLine();

			String[] score_arrays = secound_lines.split(" ");

			// ?????°???????¨???¨?????°
			double score_sum = 0;

			//n???????????????????????????????????°?????????
			for (int score_spot = 0; score_spot < score_arrays.length; score_spot++) {

				int score = Integer.parseInt(score_arrays[score_spot]);

				score_sum += score;

			}

			//???????????????
			double average = score_sum / student_num;

			//??°???a???2???
			double sequence_a_square = 0;

			//??°???a???2??????????????????
			for (int sequence_spot = 0; sequence_spot < score_arrays.length; sequence_spot++) {

				double score = Double.parseDouble(score_arrays[sequence_spot]);


				sequence_a_square += Math.pow(score - average, 2);

			}

			double distributed_a_square = sequence_a_square / student_num;

			//??°???a????????????
			double square_a = Math.sqrt(distributed_a_square);

			System.out.println(square_a);
		}

	}

} 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 input = new BufferedReader(new InputStreamReader(System.in));

		while (true) {

			String first_line = input.readLine();

			// ????????°??¨?????°
			int student_num = Integer.parseInt(first_line);

			if (student_num == 0) {

				break;

			}

			// ????????\?????¨?????°
			String secound_lines = input.readLine();

			String[] score_arrays = secound_lines.split(" ");

			// ?????°???????¨???¨?????°
			double score_sum = 0;

			//n???????????????????????????????????°?????????
			for (int score_spot = 0; score_spot < score_arrays.length; score_spot++) {

				int score = Integer.parseInt(score_arrays[score_spot]);

				score_sum += score;

			}

			//???????????????
			double average = score_sum / student_num;

			//??°???a???2???
			double sequence_a_square = 0;

			//??°???a???2??????????????????
			for (int sequence_spot = 0; sequence_spot < score_arrays.length; sequence_spot++) {

				double score = Double.parseDouble(score_arrays[sequence_spot]);


				sequence_a_square += Math.pow(score - average, 2);

			}

			double distributed_a_square = sequence_a_square / student_num;

			//??°???a????????????
			double square_a = Math.sqrt(distributed_a_square);

			System.out.println(square_a);
		}

	}

}