import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		
		
		
		while(true){
			int n = Integer.parseInt(scan.nextLine());
			if(n == 0) break;
			String str = scan.nextLine();
			String[] points = str.split(" ");
			
			double m = 0.0;
			for (int i = 0; i < n; i++) {
				m += Integer.parseInt(points[i]);
			}
			m /= n;
			
			double num = 0.0;
			for (int i = 0; i < n; i++) {
				num += Math.pow((Integer.parseInt(points[i]) - m ), 2);
			}
			
			System.out.printf("%.8f\n", (Math.sqrt(num / n)));
			
		}
				
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		
		
		
		while(true){
			int n = Integer.parseInt(scan.nextLine());
			if(n == 0) break;
			String str = scan.nextLine();
			String[] points = str.split(" ");
			
			double m = 0.0;
			for (int i = 0; i < n; i++) {
				m += Integer.parseInt(points[i]);
			}
			m /= n;
			
			double num = 0.0;
			for (int i = 0; i < n; i++) {
				num += Math.pow((Integer.parseInt(points[i]) - m ), 2);
			}
			
			System.out.printf("%.8f\n", (Math.sqrt(num / n)));
			
		}
				
	}
} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		
		
		
		while(true){
			int n = Integer.parseInt(scan.nextLine());
			if(n == 0) break;
			String str = scan.nextLine();
			String[] points = str.split(" ");
			
			double m = 0.0;
			for (int i = 0; i < n; i++) {
				m += Integer.parseInt(points[i]);
			}
			m /= n;
			
			double num = 0.0;
			for (int i = 0; i < n; i++) {
				num += Math.pow((Integer.parseInt(points[i]) - m ), 2);
			}
			
			System.out.printf("%.8f\n", (Math.sqrt(num / n)));
			
		}
				
	} main {
		Scanner scan = new Scanner(System.in);
		
		
		
		
		while(true){
			int n = Integer.parseInt(scan.nextLine());
			if(n == 0) break;
			String str = scan.nextLine();
			String[] points = str.split(" ");
			
			double m = 0.0;
			for (int i = 0; i < n; i++) {
				m += Integer.parseInt(points[i]);
			}
			m /= n;
			
			double num = 0.0;
			for (int i = 0; i < n; i++) {
				num += Math.pow((Integer.parseInt(points[i]) - m ), 2);
			}
			
			System.out.printf("%.8f\n", (Math.sqrt(num / n)));
			
		}
				
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) while(true){
			int n = Integer.parseInt(scan.nextLine());
			if(n == 0) break;
			String str = scan.nextLine();
			String[] points = str.split(" ");
			
			double m = 0.0;
			for (int i = 0; i < n; i++) {
				m += Integer.parseInt(points[i]);
			}
			m /= n;
			
			double num = 0.0;
			for (int i = 0; i < n; i++) {
				num += Math.pow((Integer.parseInt(points[i]) - m ), 2);
			}
			
			System.out.printf("%.8f\n", (Math.sqrt(num / n)));
			
		} true {
			int n = Integer.parseInt(scan.nextLine());
			if(n == 0) break;
			String str = scan.nextLine();
			String[] points = str.split(" ");
			
			double m = 0.0;
			for (int i = 0; i < n; i++) {
				m += Integer.parseInt(points[i]);
			}
			m /= n;
			
			double num = 0.0;
			for (int i = 0; i < n; i++) {
				num += Math.pow((Integer.parseInt(points[i]) - m ), 2);
			}
			
			System.out.printf("%.8f\n", (Math.sqrt(num / n)));
			
		} int n = Integer.parseInt(scan.nextLine()); n Integer.parseInt(scan.nextLine()) Integer.parseInt Integer scan.nextLine() scan.nextLine scan if(n == 0) break; n == 0 n 0 break; String str = scan.nextLine(); str scan.nextLine() scan.nextLine scan String[] points = str.split(" "); points str.split(" ") str.split str " " double m = 0.0; m 0.0 for (int i = 0; i < n; i++) {
				m += Integer.parseInt(points[i]);
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				m += Integer.parseInt(points[i]);
			} {
				m += Integer.parseInt(points[i]);
			} m += Integer.parseInt(points[i]) m Integer.parseInt(points[i]) Integer.parseInt Integer points[i] points i m /= n m n double num = 0.0; num 0.0 for (int i = 0; i < n; i++) {
				num += Math.pow((Integer.parseInt(points[i]) - m ), 2);
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				num += Math.pow((Integer.parseInt(points[i]) - m ), 2);
			} {
				num += Math.pow((Integer.parseInt(points[i]) - m ), 2);
			} num += Math.pow((Integer.parseInt(points[i]) - m ), 2) num Math.pow((Integer.parseInt(points[i]) - m ), 2) Math.pow Math (Integer.parseInt(points[i]) - m ) Integer.parseInt(points[i]) Integer.parseInt Integer points[i] points i m 2 System.out.printf("%.8f\n", (Math.sqrt(num / n))) System.out.printf System.out System System.out "%.8f\n" (Math.sqrt(num / n)) Math.sqrt Math num / n num n String[] args args public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		
		
		
		while(true){
			int n = Integer.parseInt(scan.nextLine());
			if(n == 0) break;
			String str = scan.nextLine();
			String[] points = str.split(" ");
			
			double m = 0.0;
			for (int i = 0; i < n; i++) {
				m += Integer.parseInt(points[i]);
			}
			m /= n;
			
			double num = 0.0;
			for (int i = 0; i < n; i++) {
				num += Math.pow((Integer.parseInt(points[i]) - m ), 2);
			}
			
			System.out.printf("%.8f\n", (Math.sqrt(num / n)));
			
		}
				
	}
} public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		
		
		
		while(true){
			int n = Integer.parseInt(scan.nextLine());
			if(n == 0) break;
			String str = scan.nextLine();
			String[] points = str.split(" ");
			
			double m = 0.0;
			for (int i = 0; i < n; i++) {
				m += Integer.parseInt(points[i]);
			}
			m /= n;
			
			double num = 0.0;
			for (int i = 0; i < n; i++) {
				num += Math.pow((Integer.parseInt(points[i]) - m ), 2);
			}
			
			System.out.printf("%.8f\n", (Math.sqrt(num / n)));
			
		}
				
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		
		
		
		while(true){
			int n = Integer.parseInt(scan.nextLine());
			if(n == 0) break;
			String str = scan.nextLine();
			String[] points = str.split(" ");
			
			double m = 0.0;
			for (int i = 0; i < n; i++) {
				m += Integer.parseInt(points[i]);
			}
			m /= n;
			
			double num = 0.0;
			for (int i = 0; i < n; i++) {
				num += Math.pow((Integer.parseInt(points[i]) - m ), 2);
			}
			
			System.out.printf("%.8f\n", (Math.sqrt(num / n)));
			
		}
				
	}
}