import java.util.Scanner;

public class Main {
	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		while (true) {
			int n = sc.nextInt();

			if (n == 0) {
				break;
			}

			int[] scores = new int[n];
			for (int i = 0; i < scores.length; i++) {
				scores[i] = sc.nextInt();

			}

			double average = 0, variance = 0, sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += scores[i];

			}

			average = sum / n;

			sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += (scores[i] - average) * (scores[i] - average);

			}

			variance = sum / n;

			System.out.println(Math.sqrt(variance));

		}

	}

} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		while (true) {
			int n = sc.nextInt();

			if (n == 0) {
				break;
			}

			int[] scores = new int[n];
			for (int i = 0; i < scores.length; i++) {
				scores[i] = sc.nextInt();

			}

			double average = 0, variance = 0, sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += scores[i];

			}

			average = sum / n;

			sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += (scores[i] - average) * (scores[i] - average);

			}

			variance = sum / n;

			System.out.println(Math.sqrt(variance));

		}

	}

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

		Scanner sc = new Scanner(System.in);
		while (true) {
			int n = sc.nextInt();

			if (n == 0) {
				break;
			}

			int[] scores = new int[n];
			for (int i = 0; i < scores.length; i++) {
				scores[i] = sc.nextInt();

			}

			double average = 0, variance = 0, sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += scores[i];

			}

			average = sum / n;

			sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += (scores[i] - average) * (scores[i] - average);

			}

			variance = sum / n;

			System.out.println(Math.sqrt(variance));

		}

	} main {

		Scanner sc = new Scanner(System.in);
		while (true) {
			int n = sc.nextInt();

			if (n == 0) {
				break;
			}

			int[] scores = new int[n];
			for (int i = 0; i < scores.length; i++) {
				scores[i] = sc.nextInt();

			}

			double average = 0, variance = 0, sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += scores[i];

			}

			average = sum / n;

			sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += (scores[i] - average) * (scores[i] - average);

			}

			variance = sum / n;

			System.out.println(Math.sqrt(variance));

		}

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while (true) {
			int n = sc.nextInt();

			if (n == 0) {
				break;
			}

			int[] scores = new int[n];
			for (int i = 0; i < scores.length; i++) {
				scores[i] = sc.nextInt();

			}

			double average = 0, variance = 0, sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += scores[i];

			}

			average = sum / n;

			sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += (scores[i] - average) * (scores[i] - average);

			}

			variance = sum / n;

			System.out.println(Math.sqrt(variance));

		} true {
			int n = sc.nextInt();

			if (n == 0) {
				break;
			}

			int[] scores = new int[n];
			for (int i = 0; i < scores.length; i++) {
				scores[i] = sc.nextInt();

			}

			double average = 0, variance = 0, sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += scores[i];

			}

			average = sum / n;

			sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += (scores[i] - average) * (scores[i] - average);

			}

			variance = sum / n;

			System.out.println(Math.sqrt(variance));

		} int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if (n == 0) {
				break;
			} n == 0 n 0 {
				break;
			} break; int[] scores = new int[n]; scores new int[n] n for (int i = 0; i < scores.length; i++) {
				scores[i] = sc.nextInt();

			} int i = 0; int i = 0; i 0 i < scores.length i scores.length scores scores.length i++ i++ i {
				scores[i] = sc.nextInt();

			} {
				scores[i] = sc.nextInt();

			} scores[i] = sc.nextInt() scores[i] scores i sc.nextInt() sc.nextInt sc double average = 0 average 0 variance = 0 variance 0 sum = 0; sum 0 for (int i = 0; i < scores.length; i++) {
				sum += scores[i];

			} int i = 0; int i = 0; i 0 i < scores.length i scores.length scores scores.length i++ i++ i {
				sum += scores[i];

			} {
				sum += scores[i];

			} sum += scores[i] sum scores[i] scores i average = sum / n average sum / n sum n sum = 0 sum 0 for (int i = 0; i < scores.length; i++) {
				sum += (scores[i] - average) * (scores[i] - average);

			} int i = 0; int i = 0; i 0 i < scores.length i scores.length scores scores.length i++ i++ i {
				sum += (scores[i] - average) * (scores[i] - average);

			} {
				sum += (scores[i] - average) * (scores[i] - average);

			} sum += (scores[i] - average) * (scores[i] - average) sum (scores[i] - average) * (scores[i] - average) (scores[i] - average) scores[i] scores i average (scores[i] - average) scores[i] scores i average variance = sum / n variance sum / n sum n System.out.println(Math.sqrt(variance)) System.out.println System.out System System.out Math.sqrt(variance) Math.sqrt Math variance String[] args args public class Main {
	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		while (true) {
			int n = sc.nextInt();

			if (n == 0) {
				break;
			}

			int[] scores = new int[n];
			for (int i = 0; i < scores.length; i++) {
				scores[i] = sc.nextInt();

			}

			double average = 0, variance = 0, sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += scores[i];

			}

			average = sum / n;

			sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += (scores[i] - average) * (scores[i] - average);

			}

			variance = sum / n;

			System.out.println(Math.sqrt(variance));

		}

	}

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

		Scanner sc = new Scanner(System.in);
		while (true) {
			int n = sc.nextInt();

			if (n == 0) {
				break;
			}

			int[] scores = new int[n];
			for (int i = 0; i < scores.length; i++) {
				scores[i] = sc.nextInt();

			}

			double average = 0, variance = 0, sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += scores[i];

			}

			average = sum / n;

			sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += (scores[i] - average) * (scores[i] - average);

			}

			variance = sum / n;

			System.out.println(Math.sqrt(variance));

		}

	}

} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		while (true) {
			int n = sc.nextInt();

			if (n == 0) {
				break;
			}

			int[] scores = new int[n];
			for (int i = 0; i < scores.length; i++) {
				scores[i] = sc.nextInt();

			}

			double average = 0, variance = 0, sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += scores[i];

			}

			average = sum / n;

			sum = 0;

			for (int i = 0; i < scores.length; i++) {
				sum += (scores[i] - average) * (scores[i] - average);

			}

			variance = sum / n;

			System.out.println(Math.sqrt(variance));

		}

	}

}