import java.util.Scanner;
import java.util.Arrays;

class Main{
	public static void main(String[] args){
		Scanner scanner = new Scanner(System.in);
		double sum;
		double average;
		double b;
		double answer;

		while(true){
			int n = scanner.nextInt();
			if(n == 0){
				break;
			}

			sum = 0;
			average = 0;
			b = 0; 
			answer = 0;
			int[] numbers = new int[n];
			for(int i = 0; i < n; i++){
				numbers[i] = scanner.nextInt();
				sum += numbers[i];
			}

			average = sum / n;

			for(int i = 0; i < n; i++){
				b += (numbers[i] - average) * (numbers[i] - average);
			}

			System.out.printf("%.5f", Math.sqrt(b / n));
			System.out.print("\n");

		}
	}
} import java.util.Scanner; Scanner java.util import java.util.Arrays; Arrays java.util class Main{
	public static void main(String[] args){
		Scanner scanner = new Scanner(System.in);
		double sum;
		double average;
		double b;
		double answer;

		while(true){
			int n = scanner.nextInt();
			if(n == 0){
				break;
			}

			sum = 0;
			average = 0;
			b = 0; 
			answer = 0;
			int[] numbers = new int[n];
			for(int i = 0; i < n; i++){
				numbers[i] = scanner.nextInt();
				sum += numbers[i];
			}

			average = sum / n;

			for(int i = 0; i < n; i++){
				b += (numbers[i] - average) * (numbers[i] - average);
			}

			System.out.printf("%.5f", Math.sqrt(b / n));
			System.out.print("\n");

		}
	}
} Main public static void main(String[] args){
		Scanner scanner = new Scanner(System.in);
		double sum;
		double average;
		double b;
		double answer;

		while(true){
			int n = scanner.nextInt();
			if(n == 0){
				break;
			}

			sum = 0;
			average = 0;
			b = 0; 
			answer = 0;
			int[] numbers = new int[n];
			for(int i = 0; i < n; i++){
				numbers[i] = scanner.nextInt();
				sum += numbers[i];
			}

			average = sum / n;

			for(int i = 0; i < n; i++){
				b += (numbers[i] - average) * (numbers[i] - average);
			}

			System.out.printf("%.5f", Math.sqrt(b / n));
			System.out.print("\n");

		}
	} main {
		Scanner scanner = new Scanner(System.in);
		double sum;
		double average;
		double b;
		double answer;

		while(true){
			int n = scanner.nextInt();
			if(n == 0){
				break;
			}

			sum = 0;
			average = 0;
			b = 0; 
			answer = 0;
			int[] numbers = new int[n];
			for(int i = 0; i < n; i++){
				numbers[i] = scanner.nextInt();
				sum += numbers[i];
			}

			average = sum / n;

			for(int i = 0; i < n; i++){
				b += (numbers[i] - average) * (numbers[i] - average);
			}

			System.out.printf("%.5f", Math.sqrt(b / n));
			System.out.print("\n");

		}
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) double sum; sum double average; average double b; b double answer; answer while(true){
			int n = scanner.nextInt();
			if(n == 0){
				break;
			}

			sum = 0;
			average = 0;
			b = 0; 
			answer = 0;
			int[] numbers = new int[n];
			for(int i = 0; i < n; i++){
				numbers[i] = scanner.nextInt();
				sum += numbers[i];
			}

			average = sum / n;

			for(int i = 0; i < n; i++){
				b += (numbers[i] - average) * (numbers[i] - average);
			}

			System.out.printf("%.5f", Math.sqrt(b / n));
			System.out.print("\n");

		} true {
			int n = scanner.nextInt();
			if(n == 0){
				break;
			}

			sum = 0;
			average = 0;
			b = 0; 
			answer = 0;
			int[] numbers = new int[n];
			for(int i = 0; i < n; i++){
				numbers[i] = scanner.nextInt();
				sum += numbers[i];
			}

			average = sum / n;

			for(int i = 0; i < n; i++){
				b += (numbers[i] - average) * (numbers[i] - average);
			}

			System.out.printf("%.5f", Math.sqrt(b / n));
			System.out.print("\n");

		} int n = scanner.nextInt(); n scanner.nextInt() scanner.nextInt scanner if(n == 0){
				break;
			} n == 0 n 0 {
				break;
			} break; sum = 0 sum 0 average = 0 average 0 b = 0 b 0 answer = 0 answer 0 int[] numbers = new int[n]; numbers new int[n] n for(int i = 0; i < n; i++){
				numbers[i] = scanner.nextInt();
				sum += numbers[i];
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				numbers[i] = scanner.nextInt();
				sum += numbers[i];
			} {
				numbers[i] = scanner.nextInt();
				sum += numbers[i];
			} numbers[i] = scanner.nextInt() numbers[i] numbers i scanner.nextInt() scanner.nextInt scanner sum += numbers[i] sum numbers[i] numbers i average = sum / n average sum / n sum n for(int i = 0; i < n; i++){
				b += (numbers[i] - average) * (numbers[i] - average);
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				b += (numbers[i] - average) * (numbers[i] - average);
			} {
				b += (numbers[i] - average) * (numbers[i] - average);
			} b += (numbers[i] - average) * (numbers[i] - average) b (numbers[i] - average) * (numbers[i] - average) (numbers[i] - average) numbers[i] numbers i average (numbers[i] - average) numbers[i] numbers i average System.out.printf("%.5f", Math.sqrt(b / n)) System.out.printf System.out System System.out "%.5f" Math.sqrt(b / n) Math.sqrt Math b / n b n System.out.print("\n") System.out.print System.out System System.out "\n" String[] args args
import java.util.Scanner;
import java.util.Arrays;

class Main{
	public static void main(String[] args){
		Scanner scanner = new Scanner(System.in);
		double sum;
		double average;
		double b;
		double answer;

		while(true){
			int n = scanner.nextInt();
			if(n == 0){
				break;
			}

			sum = 0;
			average = 0;
			b = 0; 
			answer = 0;
			int[] numbers = new int[n];
			for(int i = 0; i < n; i++){
				numbers[i] = scanner.nextInt();
				sum += numbers[i];
			}

			average = sum / n;

			for(int i = 0; i < n; i++){
				b += (numbers[i] - average) * (numbers[i] - average);
			}

			System.out.printf("%.5f", Math.sqrt(b / n));
			System.out.print("\n");

		}
	}
}