import java.util.Scanner;

public class Main{
	public static void main(String [] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int score[] = new int[1000];
		double avg = 0.0;
		double a = 0.0;
		while(n != 0){
			avg = 0.0;
			a = 0.0;
			for(int i = 0; i < n; i++){
				score[i] = sc.nextInt();
				avg += (double)score[i];
			}
			avg /= (double)n;
			for(int i = 0; i < n; i++){
				a += (score[i] - avg) * (score[i] - avg);
			}
			a = Math.sqrt(a/(double)n);
			System.out.println(a);
			n = sc.nextInt();
		}
	}
} import java.util.Scanner; Scanner java.util public class Main{
	public static void main(String [] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int score[] = new int[1000];
		double avg = 0.0;
		double a = 0.0;
		while(n != 0){
			avg = 0.0;
			a = 0.0;
			for(int i = 0; i < n; i++){
				score[i] = sc.nextInt();
				avg += (double)score[i];
			}
			avg /= (double)n;
			for(int i = 0; i < n; i++){
				a += (score[i] - avg) * (score[i] - avg);
			}
			a = Math.sqrt(a/(double)n);
			System.out.println(a);
			n = sc.nextInt();
		}
	}
} Main public static void main(String [] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int score[] = new int[1000];
		double avg = 0.0;
		double a = 0.0;
		while(n != 0){
			avg = 0.0;
			a = 0.0;
			for(int i = 0; i < n; i++){
				score[i] = sc.nextInt();
				avg += (double)score[i];
			}
			avg /= (double)n;
			for(int i = 0; i < n; i++){
				a += (score[i] - avg) * (score[i] - avg);
			}
			a = Math.sqrt(a/(double)n);
			System.out.println(a);
			n = sc.nextInt();
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int score[] = new int[1000];
		double avg = 0.0;
		double a = 0.0;
		while(n != 0){
			avg = 0.0;
			a = 0.0;
			for(int i = 0; i < n; i++){
				score[i] = sc.nextInt();
				avg += (double)score[i];
			}
			avg /= (double)n;
			for(int i = 0; i < n; i++){
				a += (score[i] - avg) * (score[i] - avg);
			}
			a = Math.sqrt(a/(double)n);
			System.out.println(a);
			n = sc.nextInt();
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int score[] = new int[1000]; score new int[1000] 1000 double avg = 0.0; avg 0.0 double a = 0.0; a 0.0 while(n != 0){
			avg = 0.0;
			a = 0.0;
			for(int i = 0; i < n; i++){
				score[i] = sc.nextInt();
				avg += (double)score[i];
			}
			avg /= (double)n;
			for(int i = 0; i < n; i++){
				a += (score[i] - avg) * (score[i] - avg);
			}
			a = Math.sqrt(a/(double)n);
			System.out.println(a);
			n = sc.nextInt();
		} n != 0 n 0 {
			avg = 0.0;
			a = 0.0;
			for(int i = 0; i < n; i++){
				score[i] = sc.nextInt();
				avg += (double)score[i];
			}
			avg /= (double)n;
			for(int i = 0; i < n; i++){
				a += (score[i] - avg) * (score[i] - avg);
			}
			a = Math.sqrt(a/(double)n);
			System.out.println(a);
			n = sc.nextInt();
		} avg = 0.0 avg 0.0 a = 0.0 a 0.0 for(int i = 0; i < n; i++){
				score[i] = sc.nextInt();
				avg += (double)score[i];
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				score[i] = sc.nextInt();
				avg += (double)score[i];
			} {
				score[i] = sc.nextInt();
				avg += (double)score[i];
			} score[i] = sc.nextInt() score[i] score i sc.nextInt() sc.nextInt sc avg += (double)score[i] avg (double)score[i] score i avg /= (double)n avg (double)n for(int i = 0; i < n; i++){
				a += (score[i] - avg) * (score[i] - avg);
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				a += (score[i] - avg) * (score[i] - avg);
			} {
				a += (score[i] - avg) * (score[i] - avg);
			} a += (score[i] - avg) * (score[i] - avg) a (score[i] - avg) * (score[i] - avg) (score[i] - avg) score[i] score i avg (score[i] - avg) score[i] score i avg a = Math.sqrt(a/(double)n) a Math.sqrt(a/(double)n) Math.sqrt Math a/(double)n a (double)n System.out.println(a) System.out.println System.out System System.out a n = sc.nextInt() n sc.nextInt() sc.nextInt sc String [] args args public class Main{
	public static void main(String [] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int score[] = new int[1000];
		double avg = 0.0;
		double a = 0.0;
		while(n != 0){
			avg = 0.0;
			a = 0.0;
			for(int i = 0; i < n; i++){
				score[i] = sc.nextInt();
				avg += (double)score[i];
			}
			avg /= (double)n;
			for(int i = 0; i < n; i++){
				a += (score[i] - avg) * (score[i] - avg);
			}
			a = Math.sqrt(a/(double)n);
			System.out.println(a);
			n = sc.nextInt();
		}
	}
} public class Main{
	public static void main(String [] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int score[] = new int[1000];
		double avg = 0.0;
		double a = 0.0;
		while(n != 0){
			avg = 0.0;
			a = 0.0;
			for(int i = 0; i < n; i++){
				score[i] = sc.nextInt();
				avg += (double)score[i];
			}
			avg /= (double)n;
			for(int i = 0; i < n; i++){
				a += (score[i] - avg) * (score[i] - avg);
			}
			a = Math.sqrt(a/(double)n);
			System.out.println(a);
			n = sc.nextInt();
		}
	}
} Main
import java.util.Scanner;

public class Main{
	public static void main(String [] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int score[] = new int[1000];
		double avg = 0.0;
		double a = 0.0;
		while(n != 0){
			avg = 0.0;
			a = 0.0;
			for(int i = 0; i < n; i++){
				score[i] = sc.nextInt();
				avg += (double)score[i];
			}
			avg /= (double)n;
			for(int i = 0; i < n; i++){
				a += (score[i] - avg) * (score[i] - avg);
			}
			a = Math.sqrt(a/(double)n);
			System.out.println(a);
			n = sc.nextInt();
		}
	}
}