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

class Main{

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

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

		while(true){

			int num = Integer.parseInt(br.readLine());

			if(num == 0){
				break;
			}

			String[] token = br.readLine().split(" ");
			int[] point = new int[num];
			double sum = 0;

			for(int i = 0; i < num; i++){
				point[i] = Integer.parseInt(token[i]);
				sum += point[i];
			}

			double average = sum / num;
			sum = 0;

			for(int i = 0; i < num; i++){
				sum += Math.pow(point[i] - average, 2);
			}

			double dispersion = sum / num;
			double deviation = Math.sqrt(dispersion);

			sb.append(String.format("%.8f\n", deviation));

		}

		System.out.print(sb);

	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.IOException; IOException java.io class Main{

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

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

		while(true){

			int num = Integer.parseInt(br.readLine());

			if(num == 0){
				break;
			}

			String[] token = br.readLine().split(" ");
			int[] point = new int[num];
			double sum = 0;

			for(int i = 0; i < num; i++){
				point[i] = Integer.parseInt(token[i]);
				sum += point[i];
			}

			double average = sum / num;
			sum = 0;

			for(int i = 0; i < num; i++){
				sum += Math.pow(point[i] - average, 2);
			}

			double dispersion = sum / num;
			double deviation = Math.sqrt(dispersion);

			sb.append(String.format("%.8f\n", deviation));

		}

		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();

		while(true){

			int num = Integer.parseInt(br.readLine());

			if(num == 0){
				break;
			}

			String[] token = br.readLine().split(" ");
			int[] point = new int[num];
			double sum = 0;

			for(int i = 0; i < num; i++){
				point[i] = Integer.parseInt(token[i]);
				sum += point[i];
			}

			double average = sum / num;
			sum = 0;

			for(int i = 0; i < num; i++){
				sum += Math.pow(point[i] - average, 2);
			}

			double dispersion = sum / num;
			double deviation = Math.sqrt(dispersion);

			sb.append(String.format("%.8f\n", deviation));

		}

		System.out.print(sb);

	} main {

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

		while(true){

			int num = Integer.parseInt(br.readLine());

			if(num == 0){
				break;
			}

			String[] token = br.readLine().split(" ");
			int[] point = new int[num];
			double sum = 0;

			for(int i = 0; i < num; i++){
				point[i] = Integer.parseInt(token[i]);
				sum += point[i];
			}

			double average = sum / num;
			sum = 0;

			for(int i = 0; i < num; i++){
				sum += Math.pow(point[i] - average, 2);
			}

			double dispersion = sum / num;
			double deviation = Math.sqrt(dispersion);

			sb.append(String.format("%.8f\n", deviation));

		}

		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() while(true){

			int num = Integer.parseInt(br.readLine());

			if(num == 0){
				break;
			}

			String[] token = br.readLine().split(" ");
			int[] point = new int[num];
			double sum = 0;

			for(int i = 0; i < num; i++){
				point[i] = Integer.parseInt(token[i]);
				sum += point[i];
			}

			double average = sum / num;
			sum = 0;

			for(int i = 0; i < num; i++){
				sum += Math.pow(point[i] - average, 2);
			}

			double dispersion = sum / num;
			double deviation = Math.sqrt(dispersion);

			sb.append(String.format("%.8f\n", deviation));

		} true {

			int num = Integer.parseInt(br.readLine());

			if(num == 0){
				break;
			}

			String[] token = br.readLine().split(" ");
			int[] point = new int[num];
			double sum = 0;

			for(int i = 0; i < num; i++){
				point[i] = Integer.parseInt(token[i]);
				sum += point[i];
			}

			double average = sum / num;
			sum = 0;

			for(int i = 0; i < num; i++){
				sum += Math.pow(point[i] - average, 2);
			}

			double dispersion = sum / num;
			double deviation = Math.sqrt(dispersion);

			sb.append(String.format("%.8f\n", deviation));

		} int num = Integer.parseInt(br.readLine()); num Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br if(num == 0){
				break;
			} num == 0 num 0 {
				break;
			} break; String[] token = br.readLine().split(" "); token br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " int[] point = new int[num]; point new int[num] num double sum = 0; sum 0 for(int i = 0; i < num; i++){
				point[i] = Integer.parseInt(token[i]);
				sum += point[i];
			} int i = 0; int i = 0; i 0 i < num i num i++ i++ i {
				point[i] = Integer.parseInt(token[i]);
				sum += point[i];
			} {
				point[i] = Integer.parseInt(token[i]);
				sum += point[i];
			} point[i] = Integer.parseInt(token[i]) point[i] point i Integer.parseInt(token[i]) Integer.parseInt Integer token[i] token i sum += point[i] sum point[i] point i double average = sum / num; average sum / num sum num sum = 0 sum 0 for(int i = 0; i < num; i++){
				sum += Math.pow(point[i] - average, 2);
			} int i = 0; int i = 0; i 0 i < num i num i++ i++ i {
				sum += Math.pow(point[i] - average, 2);
			} {
				sum += Math.pow(point[i] - average, 2);
			} sum += Math.pow(point[i] - average, 2) sum Math.pow(point[i] - average, 2) Math.pow Math point[i] - average point[i] point i average 2 double dispersion = sum / num; dispersion sum / num sum num double deviation = Math.sqrt(dispersion); deviation Math.sqrt(dispersion) Math.sqrt Math dispersion sb.append(String.format("%.8f\n", deviation)) sb.append sb String.format("%.8f\n", deviation) String.format String "%.8f\n" deviation System.out.print(sb) System.out.print System.out System System.out sb String[] args args
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

class Main{

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

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

		while(true){

			int num = Integer.parseInt(br.readLine());

			if(num == 0){
				break;
			}

			String[] token = br.readLine().split(" ");
			int[] point = new int[num];
			double sum = 0;

			for(int i = 0; i < num; i++){
				point[i] = Integer.parseInt(token[i]);
				sum += point[i];
			}

			double average = sum / num;
			sum = 0;

			for(int i = 0; i < num; i++){
				sum += Math.pow(point[i] - average, 2);
			}

			double dispersion = sum / num;
			double deviation = Math.sqrt(dispersion);

			sb.append(String.format("%.8f\n", deviation));

		}

		System.out.print(sb);

	}
}