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

public class Main {

	public static final int BIG_NUM  = 2000000000;
	public static final int MOD  = 1000000007;

	public static void main(String[] args) {

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

		int N;
		double M,SUM;

		try {
			while((N = Integer.parseInt(br.readLine())) != 0){

				String input[] = br.readLine().split("\\s+");
				double array[] = new double[input.length];

				SUM = 0;

				for(int i = 0; i < input.length; i++){
					array[i] = Double.parseDouble(input[i]);
					SUM += array[i];
				}

				M = SUM/(double)N;
				SUM = 0;

				for(int i = 0; i < array.length; i++){
					SUM += (array[i]-M)*(array[i]-M);
				}

				System.out.printf("%.10f\n", Math.sqrt(SUM/(double)N));
			}
		} catch (NumberFormatException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

 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 final int BIG_NUM  = 2000000000;
	public static final int MOD  = 1000000007;

	public static void main(String[] args) {

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

		int N;
		double M,SUM;

		try {
			while((N = Integer.parseInt(br.readLine())) != 0){

				String input[] = br.readLine().split("\\s+");
				double array[] = new double[input.length];

				SUM = 0;

				for(int i = 0; i < input.length; i++){
					array[i] = Double.parseDouble(input[i]);
					SUM += array[i];
				}

				M = SUM/(double)N;
				SUM = 0;

				for(int i = 0; i < array.length; i++){
					SUM += (array[i]-M)*(array[i]-M);
				}

				System.out.printf("%.10f\n", Math.sqrt(SUM/(double)N));
			}
		} catch (NumberFormatException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
} Main public static final int BIG_NUM  = 2000000000; BIG_NUM 2000000000 public static final int MOD  = 1000000007; MOD 1000000007 public static void main(String[] args) {

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

		int N;
		double M,SUM;

		try {
			while((N = Integer.parseInt(br.readLine())) != 0){

				String input[] = br.readLine().split("\\s+");
				double array[] = new double[input.length];

				SUM = 0;

				for(int i = 0; i < input.length; i++){
					array[i] = Double.parseDouble(input[i]);
					SUM += array[i];
				}

				M = SUM/(double)N;
				SUM = 0;

				for(int i = 0; i < array.length; i++){
					SUM += (array[i]-M)*(array[i]-M);
				}

				System.out.printf("%.10f\n", Math.sqrt(SUM/(double)N));
			}
		} catch (NumberFormatException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	} main {

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

		int N;
		double M,SUM;

		try {
			while((N = Integer.parseInt(br.readLine())) != 0){

				String input[] = br.readLine().split("\\s+");
				double array[] = new double[input.length];

				SUM = 0;

				for(int i = 0; i < input.length; i++){
					array[i] = Double.parseDouble(input[i]);
					SUM += array[i];
				}

				M = SUM/(double)N;
				SUM = 0;

				for(int i = 0; i < array.length; i++){
					SUM += (array[i]-M)*(array[i]-M);
				}

				System.out.printf("%.10f\n", Math.sqrt(SUM/(double)N));
			}
		} catch (NumberFormatException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int N; N double M M SUM; SUM try {
			while((N = Integer.parseInt(br.readLine())) != 0){

				String input[] = br.readLine().split("\\s+");
				double array[] = new double[input.length];

				SUM = 0;

				for(int i = 0; i < input.length; i++){
					array[i] = Double.parseDouble(input[i]);
					SUM += array[i];
				}

				M = SUM/(double)N;
				SUM = 0;

				for(int i = 0; i < array.length; i++){
					SUM += (array[i]-M)*(array[i]-M);
				}

				System.out.printf("%.10f\n", Math.sqrt(SUM/(double)N));
			}
		} catch (NumberFormatException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (NumberFormatException e) {
			e.printStackTrace();
		} NumberFormatException e {
			e.printStackTrace();
		} e.printStackTrace() e.printStackTrace e catch (IOException e) {
			e.printStackTrace();
		} IOException e {
			e.printStackTrace();
		} e.printStackTrace() e.printStackTrace e {
			while((N = Integer.parseInt(br.readLine())) != 0){

				String input[] = br.readLine().split("\\s+");
				double array[] = new double[input.length];

				SUM = 0;

				for(int i = 0; i < input.length; i++){
					array[i] = Double.parseDouble(input[i]);
					SUM += array[i];
				}

				M = SUM/(double)N;
				SUM = 0;

				for(int i = 0; i < array.length; i++){
					SUM += (array[i]-M)*(array[i]-M);
				}

				System.out.printf("%.10f\n", Math.sqrt(SUM/(double)N));
			}
		} while((N = Integer.parseInt(br.readLine())) != 0){

				String input[] = br.readLine().split("\\s+");
				double array[] = new double[input.length];

				SUM = 0;

				for(int i = 0; i < input.length; i++){
					array[i] = Double.parseDouble(input[i]);
					SUM += array[i];
				}

				M = SUM/(double)N;
				SUM = 0;

				for(int i = 0; i < array.length; i++){
					SUM += (array[i]-M)*(array[i]-M);
				}

				System.out.printf("%.10f\n", Math.sqrt(SUM/(double)N));
			} (N = Integer.parseInt(br.readLine())) != 0 (N = Integer.parseInt(br.readLine())) N Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br 0 {

				String input[] = br.readLine().split("\\s+");
				double array[] = new double[input.length];

				SUM = 0;

				for(int i = 0; i < input.length; i++){
					array[i] = Double.parseDouble(input[i]);
					SUM += array[i];
				}

				M = SUM/(double)N;
				SUM = 0;

				for(int i = 0; i < array.length; i++){
					SUM += (array[i]-M)*(array[i]-M);
				}

				System.out.printf("%.10f\n", Math.sqrt(SUM/(double)N));
			} String input[] = br.readLine().split("\\s+"); input br.readLine().split("\\s+") br.readLine().split br.readLine() br.readLine br "\\s+" double array[] = new double[input.length]; array new double[input.length] input.length input input.length SUM = 0 SUM 0 for(int i = 0; i < input.length; i++){
					array[i] = Double.parseDouble(input[i]);
					SUM += array[i];
				} int i = 0; int i = 0; i 0 i < input.length i input.length input input.length i++ i++ i {
					array[i] = Double.parseDouble(input[i]);
					SUM += array[i];
				} {
					array[i] = Double.parseDouble(input[i]);
					SUM += array[i];
				} array[i] = Double.parseDouble(input[i]) array[i] array i Double.parseDouble(input[i]) Double.parseDouble Double input[i] input i SUM += array[i] SUM array[i] array i M = SUM/(double)N M SUM/(double)N SUM (double)N SUM = 0 SUM 0 for(int i = 0; i < array.length; i++){
					SUM += (array[i]-M)*(array[i]-M);
				} int i = 0; int i = 0; i 0 i < array.length i array.length array array.length i++ i++ i {
					SUM += (array[i]-M)*(array[i]-M);
				} {
					SUM += (array[i]-M)*(array[i]-M);
				} SUM += (array[i]-M)*(array[i]-M) SUM (array[i]-M)*(array[i]-M) (array[i]-M) array[i] array i M (array[i]-M) array[i] array i M System.out.printf("%.10f\n", Math.sqrt(SUM/(double)N)) System.out.printf System.out System System.out "%.10f\n" Math.sqrt(SUM/(double)N) Math.sqrt Math SUM/(double)N SUM (double)N String[] args args public class Main {

	public static final int BIG_NUM  = 2000000000;
	public static final int MOD  = 1000000007;

	public static void main(String[] args) {

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

		int N;
		double M,SUM;

		try {
			while((N = Integer.parseInt(br.readLine())) != 0){

				String input[] = br.readLine().split("\\s+");
				double array[] = new double[input.length];

				SUM = 0;

				for(int i = 0; i < input.length; i++){
					array[i] = Double.parseDouble(input[i]);
					SUM += array[i];
				}

				M = SUM/(double)N;
				SUM = 0;

				for(int i = 0; i < array.length; i++){
					SUM += (array[i]-M)*(array[i]-M);
				}

				System.out.printf("%.10f\n", Math.sqrt(SUM/(double)N));
			}
		} catch (NumberFormatException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
} public class Main {

	public static final int BIG_NUM  = 2000000000;
	public static final int MOD  = 1000000007;

	public static void main(String[] args) {

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

		int N;
		double M,SUM;

		try {
			while((N = Integer.parseInt(br.readLine())) != 0){

				String input[] = br.readLine().split("\\s+");
				double array[] = new double[input.length];

				SUM = 0;

				for(int i = 0; i < input.length; i++){
					array[i] = Double.parseDouble(input[i]);
					SUM += array[i];
				}

				M = SUM/(double)N;
				SUM = 0;

				for(int i = 0; i < array.length; i++){
					SUM += (array[i]-M)*(array[i]-M);
				}

				System.out.printf("%.10f\n", Math.sqrt(SUM/(double)N));
			}
		} catch (NumberFormatException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	public static final int BIG_NUM  = 2000000000;
	public static final int MOD  = 1000000007;

	public static void main(String[] args) {

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

		int N;
		double M,SUM;

		try {
			while((N = Integer.parseInt(br.readLine())) != 0){

				String input[] = br.readLine().split("\\s+");
				double array[] = new double[input.length];

				SUM = 0;

				for(int i = 0; i < input.length; i++){
					array[i] = Double.parseDouble(input[i]);
					SUM += array[i];
				}

				M = SUM/(double)N;
				SUM = 0;

				for(int i = 0; i < array.length; i++){
					SUM += (array[i]-M)*(array[i]-M);
				}

				System.out.printf("%.10f\n", Math.sqrt(SUM/(double)N));
			}
		} catch (NumberFormatException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}


