import java.util.*;

public class Main{
	private static final Scanner scan = new Scanner(System.in);

	public static void main(String[] args){
		List<Double> list = new ArrayList<Double>();
		double al = 0;
		for(;;){
			double n = scan.nextDouble();
			if(n == 0){
				break;
			}
			Double[] s = new Double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				s[i]  = scan.nextDouble();
				sum += s[i];
			}
			double m = sum / n;
			double a1 = 0;
			for(int i = 0; i < n; i++){
				a1 += Math.pow(s[i] - m, 2);
			}
			al = Math.sqrt(a1 / n);
			list.add(al);
		}

		for(double d : list){
			System.out.printf("%f\n", d);
		}
	}
} import java.util.*; util.* java public class Main{
	private static final Scanner scan = new Scanner(System.in);

	public static void main(String[] args){
		List<Double> list = new ArrayList<Double>();
		double al = 0;
		for(;;){
			double n = scan.nextDouble();
			if(n == 0){
				break;
			}
			Double[] s = new Double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				s[i]  = scan.nextDouble();
				sum += s[i];
			}
			double m = sum / n;
			double a1 = 0;
			for(int i = 0; i < n; i++){
				a1 += Math.pow(s[i] - m, 2);
			}
			al = Math.sqrt(a1 / n);
			list.add(al);
		}

		for(double d : list){
			System.out.printf("%f\n", d);
		}
	}
} Main private static final Scanner scan = new Scanner(System.in); scan new Scanner(System.in) public static void main(String[] args){
		List<Double> list = new ArrayList<Double>();
		double al = 0;
		for(;;){
			double n = scan.nextDouble();
			if(n == 0){
				break;
			}
			Double[] s = new Double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				s[i]  = scan.nextDouble();
				sum += s[i];
			}
			double m = sum / n;
			double a1 = 0;
			for(int i = 0; i < n; i++){
				a1 += Math.pow(s[i] - m, 2);
			}
			al = Math.sqrt(a1 / n);
			list.add(al);
		}

		for(double d : list){
			System.out.printf("%f\n", d);
		}
	} main {
		List<Double> list = new ArrayList<Double>();
		double al = 0;
		for(;;){
			double n = scan.nextDouble();
			if(n == 0){
				break;
			}
			Double[] s = new Double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				s[i]  = scan.nextDouble();
				sum += s[i];
			}
			double m = sum / n;
			double a1 = 0;
			for(int i = 0; i < n; i++){
				a1 += Math.pow(s[i] - m, 2);
			}
			al = Math.sqrt(a1 / n);
			list.add(al);
		}

		for(double d : list){
			System.out.printf("%f\n", d);
		}
	} List<Double> list = new ArrayList<Double>(); list new ArrayList<Double>() double al = 0; al 0 for(;;){
			double n = scan.nextDouble();
			if(n == 0){
				break;
			}
			Double[] s = new Double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				s[i]  = scan.nextDouble();
				sum += s[i];
			}
			double m = sum / n;
			double a1 = 0;
			for(int i = 0; i < n; i++){
				a1 += Math.pow(s[i] - m, 2);
			}
			al = Math.sqrt(a1 / n);
			list.add(al);
		} ; {
			double n = scan.nextDouble();
			if(n == 0){
				break;
			}
			Double[] s = new Double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				s[i]  = scan.nextDouble();
				sum += s[i];
			}
			double m = sum / n;
			double a1 = 0;
			for(int i = 0; i < n; i++){
				a1 += Math.pow(s[i] - m, 2);
			}
			al = Math.sqrt(a1 / n);
			list.add(al);
		} {
			double n = scan.nextDouble();
			if(n == 0){
				break;
			}
			Double[] s = new Double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				s[i]  = scan.nextDouble();
				sum += s[i];
			}
			double m = sum / n;
			double a1 = 0;
			for(int i = 0; i < n; i++){
				a1 += Math.pow(s[i] - m, 2);
			}
			al = Math.sqrt(a1 / n);
			list.add(al);
		} double n = scan.nextDouble(); n scan.nextDouble() scan.nextDouble scan if(n == 0){
				break;
			} n == 0 n 0 {
				break;
			} break; Double[] s = new Double[(int) n]; s new Double[(int) n] (int) n double sum = 0; sum 0 for(int i = 0; i < n; i++){
				s[i]  = scan.nextDouble();
				sum += s[i];
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				s[i]  = scan.nextDouble();
				sum += s[i];
			} {
				s[i]  = scan.nextDouble();
				sum += s[i];
			} s[i]  = scan.nextDouble() s[i] s i scan.nextDouble() scan.nextDouble scan sum += s[i] sum s[i] s i double m = sum / n; m sum / n sum n double a1 = 0; a1 0 for(int i = 0; i < n; i++){
				a1 += Math.pow(s[i] - m, 2);
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				a1 += Math.pow(s[i] - m, 2);
			} {
				a1 += Math.pow(s[i] - m, 2);
			} a1 += Math.pow(s[i] - m, 2) a1 Math.pow(s[i] - m, 2) Math.pow Math s[i] - m s[i] s i m 2 al = Math.sqrt(a1 / n) al Math.sqrt(a1 / n) Math.sqrt Math a1 / n a1 n list.add(al) list.add list al for(double d : list){
			System.out.printf("%f\n", d);
		} double d list {
			System.out.printf("%f\n", d);
		} {
			System.out.printf("%f\n", d);
		} System.out.printf("%f\n", d) System.out.printf System.out System System.out "%f\n" d String[] args args public class Main{
	private static final Scanner scan = new Scanner(System.in);

	public static void main(String[] args){
		List<Double> list = new ArrayList<Double>();
		double al = 0;
		for(;;){
			double n = scan.nextDouble();
			if(n == 0){
				break;
			}
			Double[] s = new Double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				s[i]  = scan.nextDouble();
				sum += s[i];
			}
			double m = sum / n;
			double a1 = 0;
			for(int i = 0; i < n; i++){
				a1 += Math.pow(s[i] - m, 2);
			}
			al = Math.sqrt(a1 / n);
			list.add(al);
		}

		for(double d : list){
			System.out.printf("%f\n", d);
		}
	}
} public class Main{
	private static final Scanner scan = new Scanner(System.in);

	public static void main(String[] args){
		List<Double> list = new ArrayList<Double>();
		double al = 0;
		for(;;){
			double n = scan.nextDouble();
			if(n == 0){
				break;
			}
			Double[] s = new Double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				s[i]  = scan.nextDouble();
				sum += s[i];
			}
			double m = sum / n;
			double a1 = 0;
			for(int i = 0; i < n; i++){
				a1 += Math.pow(s[i] - m, 2);
			}
			al = Math.sqrt(a1 / n);
			list.add(al);
		}

		for(double d : list){
			System.out.printf("%f\n", d);
		}
	}
} Main
import java.util.*;

public class Main{
	private static final Scanner scan = new Scanner(System.in);

	public static void main(String[] args){
		List<Double> list = new ArrayList<Double>();
		double al = 0;
		for(;;){
			double n = scan.nextDouble();
			if(n == 0){
				break;
			}
			Double[] s = new Double[(int) n];
			double sum = 0;
			for(int i = 0; i < n; i++){
				s[i]  = scan.nextDouble();
				sum += s[i];
			}
			double m = sum / n;
			double a1 = 0;
			for(int i = 0; i < n; i++){
				a1 += Math.pow(s[i] - m, 2);
			}
			al = Math.sqrt(a1 / n);
			list.add(al);
		}

		for(double d : list){
			System.out.printf("%f\n", d);
		}
	}
}