import java.io.IOException;
import java.util.Scanner;
class Main{
	public static void main(String[] args)throws NumberFormatException, IOException{
		//System.out.println(" ");
		Scanner scan = new Scanner(System.in);
		int n = 1;
		while(n != 0){
			n =scan.nextInt();
			if (n==0){
				break;
			}
			int[] score = new int[n];
			double heikin = 0.0;
			for(int i=0;i<n; i++){
				score[i] = scan.nextInt();
				heikin += score[i];
			}
			heikin /= n;
			double keisan = 0.0;
			for(int i=0; i<n; i++){
				keisan += (score[i] - heikin) * (score[i] - heikin);
			}
			keisan /= n;
			keisan = Math.sqrt(keisan);
			System.out.println(keisan);
		}
	}
} import java.io.IOException; IOException java.io import java.util.Scanner; Scanner java.util class Main{
	public static void main(String[] args)throws NumberFormatException, IOException{
		//System.out.println(" ");
		Scanner scan = new Scanner(System.in);
		int n = 1;
		while(n != 0){
			n =scan.nextInt();
			if (n==0){
				break;
			}
			int[] score = new int[n];
			double heikin = 0.0;
			for(int i=0;i<n; i++){
				score[i] = scan.nextInt();
				heikin += score[i];
			}
			heikin /= n;
			double keisan = 0.0;
			for(int i=0; i<n; i++){
				keisan += (score[i] - heikin) * (score[i] - heikin);
			}
			keisan /= n;
			keisan = Math.sqrt(keisan);
			System.out.println(keisan);
		}
	}
} Main public static void main(String[] args)throws NumberFormatException, IOException{
		//System.out.println(" ");
		Scanner scan = new Scanner(System.in);
		int n = 1;
		while(n != 0){
			n =scan.nextInt();
			if (n==0){
				break;
			}
			int[] score = new int[n];
			double heikin = 0.0;
			for(int i=0;i<n; i++){
				score[i] = scan.nextInt();
				heikin += score[i];
			}
			heikin /= n;
			double keisan = 0.0;
			for(int i=0; i<n; i++){
				keisan += (score[i] - heikin) * (score[i] - heikin);
			}
			keisan /= n;
			keisan = Math.sqrt(keisan);
			System.out.println(keisan);
		}
	} main {
		//System.out.println(" ");
		Scanner scan = new Scanner(System.in);
		int n = 1;
		while(n != 0){
			n =scan.nextInt();
			if (n==0){
				break;
			}
			int[] score = new int[n];
			double heikin = 0.0;
			for(int i=0;i<n; i++){
				score[i] = scan.nextInt();
				heikin += score[i];
			}
			heikin /= n;
			double keisan = 0.0;
			for(int i=0; i<n; i++){
				keisan += (score[i] - heikin) * (score[i] - heikin);
			}
			keisan /= n;
			keisan = Math.sqrt(keisan);
			System.out.println(keisan);
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int n = 1; n 1 while(n != 0){
			n =scan.nextInt();
			if (n==0){
				break;
			}
			int[] score = new int[n];
			double heikin = 0.0;
			for(int i=0;i<n; i++){
				score[i] = scan.nextInt();
				heikin += score[i];
			}
			heikin /= n;
			double keisan = 0.0;
			for(int i=0; i<n; i++){
				keisan += (score[i] - heikin) * (score[i] - heikin);
			}
			keisan /= n;
			keisan = Math.sqrt(keisan);
			System.out.println(keisan);
		} n != 0 n 0 {
			n =scan.nextInt();
			if (n==0){
				break;
			}
			int[] score = new int[n];
			double heikin = 0.0;
			for(int i=0;i<n; i++){
				score[i] = scan.nextInt();
				heikin += score[i];
			}
			heikin /= n;
			double keisan = 0.0;
			for(int i=0; i<n; i++){
				keisan += (score[i] - heikin) * (score[i] - heikin);
			}
			keisan /= n;
			keisan = Math.sqrt(keisan);
			System.out.println(keisan);
		} n =scan.nextInt() n scan.nextInt() scan.nextInt scan if (n==0){
				break;
			} n==0 n 0 {
				break;
			} break; int[] score = new int[n]; score new int[n] n double heikin = 0.0; heikin 0.0 for(int i=0;i<n; i++){
				score[i] = scan.nextInt();
				heikin += score[i];
			} int i=0; int i=0; i 0 i<n i n i++ i++ i {
				score[i] = scan.nextInt();
				heikin += score[i];
			} {
				score[i] = scan.nextInt();
				heikin += score[i];
			} score[i] = scan.nextInt() score[i] score i scan.nextInt() scan.nextInt scan heikin += score[i] heikin score[i] score i heikin /= n heikin n double keisan = 0.0; keisan 0.0 for(int i=0; i<n; i++){
				keisan += (score[i] - heikin) * (score[i] - heikin);
			} int i=0; int i=0; i 0 i<n i n i++ i++ i {
				keisan += (score[i] - heikin) * (score[i] - heikin);
			} {
				keisan += (score[i] - heikin) * (score[i] - heikin);
			} keisan += (score[i] - heikin) * (score[i] - heikin) keisan (score[i] - heikin) * (score[i] - heikin) (score[i] - heikin) score[i] score i heikin (score[i] - heikin) score[i] score i heikin keisan /= n keisan n keisan = Math.sqrt(keisan) keisan Math.sqrt(keisan) Math.sqrt Math keisan System.out.println(keisan) System.out.println System.out System System.out keisan String[] args args
import java.io.IOException;
import java.util.Scanner;
class Main{
	public static void main(String[] args)throws NumberFormatException, IOException{
		//System.out.println(" ");
		Scanner scan = new Scanner(System.in);
		int n = 1;
		while(n != 0){
			n =scan.nextInt();
			if (n==0){
				break;
			}
			int[] score = new int[n];
			double heikin = 0.0;
			for(int i=0;i<n; i++){
				score[i] = scan.nextInt();
				heikin += score[i];
			}
			heikin /= n;
			double keisan = 0.0;
			for(int i=0; i<n; i++){
				keisan += (score[i] - heikin) * (score[i] - heikin);
			}
			keisan /= n;
			keisan = Math.sqrt(keisan);
			System.out.println(keisan);
		}
	}
}