import java.util.*;

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

		List<Double> listAl = new ArrayList<Double>();
		Scanner scan = new Scanner(System.in);
		double n = scan.nextDouble();
		while(n != 0){
			double[] sc = new double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				double s = scan.nextDouble();
				sc[i] = s;
				sum += s;
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++){
				a += Math.pow((sc[i] - m), 2);
			}
			double al = Math.sqrt(a / n);
			listAl.add(al);
			n = scan.nextDouble();
		}

		for(double a : listAl){
			System.out.println(a);
		}
	}
} import java.util.*; util.* java public class Main{
	public static void main(String[] args){

		List<Double> listAl = new ArrayList<Double>();
		Scanner scan = new Scanner(System.in);
		double n = scan.nextDouble();
		while(n != 0){
			double[] sc = new double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				double s = scan.nextDouble();
				sc[i] = s;
				sum += s;
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++){
				a += Math.pow((sc[i] - m), 2);
			}
			double al = Math.sqrt(a / n);
			listAl.add(al);
			n = scan.nextDouble();
		}

		for(double a : listAl){
			System.out.println(a);
		}
	}
} Main public static void main(String[] args){

		List<Double> listAl = new ArrayList<Double>();
		Scanner scan = new Scanner(System.in);
		double n = scan.nextDouble();
		while(n != 0){
			double[] sc = new double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				double s = scan.nextDouble();
				sc[i] = s;
				sum += s;
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++){
				a += Math.pow((sc[i] - m), 2);
			}
			double al = Math.sqrt(a / n);
			listAl.add(al);
			n = scan.nextDouble();
		}

		for(double a : listAl){
			System.out.println(a);
		}
	} main {

		List<Double> listAl = new ArrayList<Double>();
		Scanner scan = new Scanner(System.in);
		double n = scan.nextDouble();
		while(n != 0){
			double[] sc = new double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				double s = scan.nextDouble();
				sc[i] = s;
				sum += s;
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++){
				a += Math.pow((sc[i] - m), 2);
			}
			double al = Math.sqrt(a / n);
			listAl.add(al);
			n = scan.nextDouble();
		}

		for(double a : listAl){
			System.out.println(a);
		}
	} List<Double> listAl = new ArrayList<Double>(); listAl new ArrayList<Double>() Scanner scan = new Scanner(System.in); scan new Scanner(System.in) double n = scan.nextDouble(); n scan.nextDouble() scan.nextDouble scan while(n != 0){
			double[] sc = new double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				double s = scan.nextDouble();
				sc[i] = s;
				sum += s;
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++){
				a += Math.pow((sc[i] - m), 2);
			}
			double al = Math.sqrt(a / n);
			listAl.add(al);
			n = scan.nextDouble();
		} n != 0 n 0 {
			double[] sc = new double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				double s = scan.nextDouble();
				sc[i] = s;
				sum += s;
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++){
				a += Math.pow((sc[i] - m), 2);
			}
			double al = Math.sqrt(a / n);
			listAl.add(al);
			n = scan.nextDouble();
		} double[] sc = new double[(int) n]; sc new double[(int) n] (int) n double sum = 0; sum 0 for(int i = 0; i < n; i++){
				double s = scan.nextDouble();
				sc[i] = s;
				sum += s;
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				double s = scan.nextDouble();
				sc[i] = s;
				sum += s;
			} {
				double s = scan.nextDouble();
				sc[i] = s;
				sum += s;
			} double s = scan.nextDouble(); s scan.nextDouble() scan.nextDouble scan sc[i] = s sc[i] sc i s sum += s sum s double m = sum / n; m sum / n sum n double a = 0; a 0 for(int i = 0; i < n; i++){
				a += Math.pow((sc[i] - m), 2);
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				a += Math.pow((sc[i] - m), 2);
			} {
				a += Math.pow((sc[i] - m), 2);
			} a += Math.pow((sc[i] - m), 2) a Math.pow((sc[i] - m), 2) Math.pow Math (sc[i] - m) sc[i] sc i m 2 double al = Math.sqrt(a / n); al Math.sqrt(a / n) Math.sqrt Math a / n a n listAl.add(al) listAl.add listAl al n = scan.nextDouble() n scan.nextDouble() scan.nextDouble scan for(double a : listAl){
			System.out.println(a);
		} double a listAl {
			System.out.println(a);
		} {
			System.out.println(a);
		} System.out.println(a) System.out.println System.out System System.out a String[] args args public class Main{
	public static void main(String[] args){

		List<Double> listAl = new ArrayList<Double>();
		Scanner scan = new Scanner(System.in);
		double n = scan.nextDouble();
		while(n != 0){
			double[] sc = new double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				double s = scan.nextDouble();
				sc[i] = s;
				sum += s;
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++){
				a += Math.pow((sc[i] - m), 2);
			}
			double al = Math.sqrt(a / n);
			listAl.add(al);
			n = scan.nextDouble();
		}

		for(double a : listAl){
			System.out.println(a);
		}
	}
} public class Main{
	public static void main(String[] args){

		List<Double> listAl = new ArrayList<Double>();
		Scanner scan = new Scanner(System.in);
		double n = scan.nextDouble();
		while(n != 0){
			double[] sc = new double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				double s = scan.nextDouble();
				sc[i] = s;
				sum += s;
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++){
				a += Math.pow((sc[i] - m), 2);
			}
			double al = Math.sqrt(a / n);
			listAl.add(al);
			n = scan.nextDouble();
		}

		for(double a : listAl){
			System.out.println(a);
		}
	}
} Main
import java.util.*;

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

		List<Double> listAl = new ArrayList<Double>();
		Scanner scan = new Scanner(System.in);
		double n = scan.nextDouble();
		while(n != 0){
			double[] sc = new double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				double s = scan.nextDouble();
				sc[i] = s;
				sum += s;
			}
			double m = sum / n;
			double a = 0;
			for(int i = 0; i < n; i++){
				a += Math.pow((sc[i] - m), 2);
			}
			double al = Math.sqrt(a / n);
			listAl.add(al);
			n = scan.nextDouble();
		}

		for(double a : listAl){
			System.out.println(a);
		}
	}
}