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));
		StringBuilder sb = new StringBuilder();

		for(;;) {
			String line = br.readLine();
			if(line.equals("0")) {
				break;
			}
			int n = Integer.parseInt(line);
			String[] set = br.readLine().split(" ");
			int[] s = new int[n];
			double sum = 0;
			for(int i = 0; i < n; i++) {
				s[i] = Integer.parseInt(set[i]);
				sum += s[i];
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++) {
				 a += Math.pow(s[i] - m , 2);
			}

			double alpha = Math.sqrt(a / n);

			sb.append(alpha).append("\n");

		}
		System.out.print(sb);
	}
} 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));
		StringBuilder sb = new StringBuilder();

		for(;;) {
			String line = br.readLine();
			if(line.equals("0")) {
				break;
			}
			int n = Integer.parseInt(line);
			String[] set = br.readLine().split(" ");
			int[] s = new int[n];
			double sum = 0;
			for(int i = 0; i < n; i++) {
				s[i] = Integer.parseInt(set[i]);
				sum += s[i];
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++) {
				 a += Math.pow(s[i] - m , 2);
			}

			double alpha = Math.sqrt(a / n);

			sb.append(alpha).append("\n");

		}
		System.out.print(sb);
	}
} Main public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();

		for(;;) {
			String line = br.readLine();
			if(line.equals("0")) {
				break;
			}
			int n = Integer.parseInt(line);
			String[] set = br.readLine().split(" ");
			int[] s = new int[n];
			double sum = 0;
			for(int i = 0; i < n; i++) {
				s[i] = Integer.parseInt(set[i]);
				sum += s[i];
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++) {
				 a += Math.pow(s[i] - m , 2);
			}

			double alpha = Math.sqrt(a / n);

			sb.append(alpha).append("\n");

		}
		System.out.print(sb);
	} main {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();

		for(;;) {
			String line = br.readLine();
			if(line.equals("0")) {
				break;
			}
			int n = Integer.parseInt(line);
			String[] set = br.readLine().split(" ");
			int[] s = new int[n];
			double sum = 0;
			for(int i = 0; i < n; i++) {
				s[i] = Integer.parseInt(set[i]);
				sum += s[i];
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++) {
				 a += Math.pow(s[i] - m , 2);
			}

			double alpha = Math.sqrt(a / n);

			sb.append(alpha).append("\n");

		}
		System.out.print(sb);
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) StringBuilder sb = new StringBuilder(); sb new StringBuilder() for(;;) {
			String line = br.readLine();
			if(line.equals("0")) {
				break;
			}
			int n = Integer.parseInt(line);
			String[] set = br.readLine().split(" ");
			int[] s = new int[n];
			double sum = 0;
			for(int i = 0; i < n; i++) {
				s[i] = Integer.parseInt(set[i]);
				sum += s[i];
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++) {
				 a += Math.pow(s[i] - m , 2);
			}

			double alpha = Math.sqrt(a / n);

			sb.append(alpha).append("\n");

		} ; {
			String line = br.readLine();
			if(line.equals("0")) {
				break;
			}
			int n = Integer.parseInt(line);
			String[] set = br.readLine().split(" ");
			int[] s = new int[n];
			double sum = 0;
			for(int i = 0; i < n; i++) {
				s[i] = Integer.parseInt(set[i]);
				sum += s[i];
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++) {
				 a += Math.pow(s[i] - m , 2);
			}

			double alpha = Math.sqrt(a / n);

			sb.append(alpha).append("\n");

		} {
			String line = br.readLine();
			if(line.equals("0")) {
				break;
			}
			int n = Integer.parseInt(line);
			String[] set = br.readLine().split(" ");
			int[] s = new int[n];
			double sum = 0;
			for(int i = 0; i < n; i++) {
				s[i] = Integer.parseInt(set[i]);
				sum += s[i];
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++) {
				 a += Math.pow(s[i] - m , 2);
			}

			double alpha = Math.sqrt(a / n);

			sb.append(alpha).append("\n");

		} String line = br.readLine(); line br.readLine() br.readLine br if(line.equals("0")) {
				break;
			} line.equals("0") line.equals line "0" {
				break;
			} break; int n = Integer.parseInt(line); n Integer.parseInt(line) Integer.parseInt Integer line String[] set = br.readLine().split(" "); set br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " int[] s = new int[n]; s new int[n] n double sum = 0; sum 0 for(int i = 0; i < n; i++) {
				s[i] = Integer.parseInt(set[i]);
				sum += s[i];
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				s[i] = Integer.parseInt(set[i]);
				sum += s[i];
			} {
				s[i] = Integer.parseInt(set[i]);
				sum += s[i];
			} s[i] = Integer.parseInt(set[i]) s[i] s i Integer.parseInt(set[i]) Integer.parseInt Integer set[i] set i sum += s[i] sum s[i] s i double m = sum / n; m sum / n sum n double a = 0; a 0 for(int i = 0; i < n; i++) {
				 a += Math.pow(s[i] - m , 2);
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				 a += Math.pow(s[i] - m , 2);
			} {
				 a += Math.pow(s[i] - m , 2);
			} a += Math.pow(s[i] - m , 2) a Math.pow(s[i] - m , 2) Math.pow Math s[i] - m s[i] s i m 2 double alpha = Math.sqrt(a / n); alpha Math.sqrt(a / n) Math.sqrt Math a / n a n sb.append(alpha).append("\n") sb.append(alpha).append sb.append(alpha) sb.append sb alpha "\n" System.out.print(sb) System.out.print System.out System System.out sb String[] args args public class Main {

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

		for(;;) {
			String line = br.readLine();
			if(line.equals("0")) {
				break;
			}
			int n = Integer.parseInt(line);
			String[] set = br.readLine().split(" ");
			int[] s = new int[n];
			double sum = 0;
			for(int i = 0; i < n; i++) {
				s[i] = Integer.parseInt(set[i]);
				sum += s[i];
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++) {
				 a += Math.pow(s[i] - m , 2);
			}

			double alpha = Math.sqrt(a / n);

			sb.append(alpha).append("\n");

		}
		System.out.print(sb);
	}
} public class Main {

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

		for(;;) {
			String line = br.readLine();
			if(line.equals("0")) {
				break;
			}
			int n = Integer.parseInt(line);
			String[] set = br.readLine().split(" ");
			int[] s = new int[n];
			double sum = 0;
			for(int i = 0; i < n; i++) {
				s[i] = Integer.parseInt(set[i]);
				sum += s[i];
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++) {
				 a += Math.pow(s[i] - m , 2);
			}

			double alpha = Math.sqrt(a / n);

			sb.append(alpha).append("\n");

		}
		System.out.print(sb);
	}
} 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));
		StringBuilder sb = new StringBuilder();

		for(;;) {
			String line = br.readLine();
			if(line.equals("0")) {
				break;
			}
			int n = Integer.parseInt(line);
			String[] set = br.readLine().split(" ");
			int[] s = new int[n];
			double sum = 0;
			for(int i = 0; i < n; i++) {
				s[i] = Integer.parseInt(set[i]);
				sum += s[i];
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++) {
				 a += Math.pow(s[i] - m , 2);
			}

			double alpha = Math.sqrt(a / n);

			sb.append(alpha).append("\n");

		}
		System.out.print(sb);
	}
}