import java.util.Scanner;

class Main {
	public static void main(String args[]){	

		Scanner scan = new Scanner(System.in);

		int n;
		while(true){
			n = scan.nextInt();
			if(n == 0)break;
			double sum = 0;
			double ave = 0;
			double var = 0;
		
			int a[];
			a = new int[n];
	
			for(int i = 0;i < n;i++){
				a[i] = scan.nextInt();
			}
		
			for(int i = 0; i < n; i++){
				sum += a[i];
			}
		
			ave = sum / n;
		
			for(int i = 0; i < n; i++){
				var += Math.pow((a[i] - ave),2);
			}
		
			System.out.println(Math.sqrt(var/n));
		}
	}
	
} import java.util.Scanner; Scanner java.util class Main {
	public static void main(String args[]){	

		Scanner scan = new Scanner(System.in);

		int n;
		while(true){
			n = scan.nextInt();
			if(n == 0)break;
			double sum = 0;
			double ave = 0;
			double var = 0;
		
			int a[];
			a = new int[n];
	
			for(int i = 0;i < n;i++){
				a[i] = scan.nextInt();
			}
		
			for(int i = 0; i < n; i++){
				sum += a[i];
			}
		
			ave = sum / n;
		
			for(int i = 0; i < n; i++){
				var += Math.pow((a[i] - ave),2);
			}
		
			System.out.println(Math.sqrt(var/n));
		}
	}
	
} Main public static void main(String args[]){	

		Scanner scan = new Scanner(System.in);

		int n;
		while(true){
			n = scan.nextInt();
			if(n == 0)break;
			double sum = 0;
			double ave = 0;
			double var = 0;
		
			int a[];
			a = new int[n];
	
			for(int i = 0;i < n;i++){
				a[i] = scan.nextInt();
			}
		
			for(int i = 0; i < n; i++){
				sum += a[i];
			}
		
			ave = sum / n;
		
			for(int i = 0; i < n; i++){
				var += Math.pow((a[i] - ave),2);
			}
		
			System.out.println(Math.sqrt(var/n));
		}
	} main {	

		Scanner scan = new Scanner(System.in);

		int n;
		while(true){
			n = scan.nextInt();
			if(n == 0)break;
			double sum = 0;
			double ave = 0;
			double var = 0;
		
			int a[];
			a = new int[n];
	
			for(int i = 0;i < n;i++){
				a[i] = scan.nextInt();
			}
		
			for(int i = 0; i < n; i++){
				sum += a[i];
			}
		
			ave = sum / n;
		
			for(int i = 0; i < n; i++){
				var += Math.pow((a[i] - ave),2);
			}
		
			System.out.println(Math.sqrt(var/n));
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int n; n while(true){
			n = scan.nextInt();
			if(n == 0)break;
			double sum = 0;
			double ave = 0;
			double var = 0;
		
			int a[];
			a = new int[n];
	
			for(int i = 0;i < n;i++){
				a[i] = scan.nextInt();
			}
		
			for(int i = 0; i < n; i++){
				sum += a[i];
			}
		
			ave = sum / n;
		
			for(int i = 0; i < n; i++){
				var += Math.pow((a[i] - ave),2);
			}
		
			System.out.println(Math.sqrt(var/n));
		} true {
			n = scan.nextInt();
			if(n == 0)break;
			double sum = 0;
			double ave = 0;
			double var = 0;
		
			int a[];
			a = new int[n];
	
			for(int i = 0;i < n;i++){
				a[i] = scan.nextInt();
			}
		
			for(int i = 0; i < n; i++){
				sum += a[i];
			}
		
			ave = sum / n;
		
			for(int i = 0; i < n; i++){
				var += Math.pow((a[i] - ave),2);
			}
		
			System.out.println(Math.sqrt(var/n));
		} n = scan.nextInt() n scan.nextInt() scan.nextInt scan if(n == 0)break; n == 0 n 0 break; double sum = 0; sum 0 double ave = 0; ave 0 double var = 0; var 0 int a[]; a a = new int[n] a new int[n] n for(int i = 0;i < n;i++){
				a[i] = scan.nextInt();
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				a[i] = scan.nextInt();
			} {
				a[i] = scan.nextInt();
			} a[i] = scan.nextInt() a[i] a i scan.nextInt() scan.nextInt scan for(int i = 0; i < n; i++){
				sum += a[i];
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				sum += a[i];
			} {
				sum += a[i];
			} sum += a[i] sum a[i] a i ave = sum / n ave sum / n sum n for(int i = 0; i < n; i++){
				var += Math.pow((a[i] - ave),2);
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				var += Math.pow((a[i] - ave),2);
			} {
				var += Math.pow((a[i] - ave),2);
			} var += Math.pow((a[i] - ave),2) var Math.pow((a[i] - ave),2) Math.pow Math (a[i] - ave) a[i] a i ave 2 System.out.println(Math.sqrt(var/n)) System.out.println System.out System System.out Math.sqrt(var/n) Math.sqrt Math var/n var n String args[] args
import java.util.Scanner;

class Main {
	public static void main(String args[]){	

		Scanner scan = new Scanner(System.in);

		int n;
		while(true){
			n = scan.nextInt();
			if(n == 0)break;
			double sum = 0;
			double ave = 0;
			double var = 0;
		
			int a[];
			a = new int[n];
	
			for(int i = 0;i < n;i++){
				a[i] = scan.nextInt();
			}
		
			for(int i = 0; i < n; i++){
				sum += a[i];
			}
		
			ave = sum / n;
		
			for(int i = 0; i < n; i++){
				var += Math.pow((a[i] - ave),2);
			}
		
			System.out.println(Math.sqrt(var/n));
		}
	}
	
}