import java.util.Scanner;
import java.util.*;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		while (n != 0) {
			double sum = 0;
			List<Integer> vals = new ArrayList<Integer>();
			for (int i = 0; i < n; i++) {
				int a = sc.nextInt();
				vals.add(a);
				sum += a;
			}
			double ave = sum/n;
			sum = 0;
			for (int i = 0; i < n; i++) {
				sum += (vals.get(i) - ave)*(vals.get(i) - ave);
			}
			double a = sum/n;
			a = Math.sqrt(a);
			System.out.println(String.format("%.5f", a));
			n = sc.nextInt();
		}
	}
}
 import java.util.Scanner; Scanner java.util import java.util.*; util.* java public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		while (n != 0) {
			double sum = 0;
			List<Integer> vals = new ArrayList<Integer>();
			for (int i = 0; i < n; i++) {
				int a = sc.nextInt();
				vals.add(a);
				sum += a;
			}
			double ave = sum/n;
			sum = 0;
			for (int i = 0; i < n; i++) {
				sum += (vals.get(i) - ave)*(vals.get(i) - ave);
			}
			double a = sum/n;
			a = Math.sqrt(a);
			System.out.println(String.format("%.5f", a));
			n = sc.nextInt();
		}
	}
} Main public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		while (n != 0) {
			double sum = 0;
			List<Integer> vals = new ArrayList<Integer>();
			for (int i = 0; i < n; i++) {
				int a = sc.nextInt();
				vals.add(a);
				sum += a;
			}
			double ave = sum/n;
			sum = 0;
			for (int i = 0; i < n; i++) {
				sum += (vals.get(i) - ave)*(vals.get(i) - ave);
			}
			double a = sum/n;
			a = Math.sqrt(a);
			System.out.println(String.format("%.5f", a));
			n = sc.nextInt();
		}
	} main {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		while (n != 0) {
			double sum = 0;
			List<Integer> vals = new ArrayList<Integer>();
			for (int i = 0; i < n; i++) {
				int a = sc.nextInt();
				vals.add(a);
				sum += a;
			}
			double ave = sum/n;
			sum = 0;
			for (int i = 0; i < n; i++) {
				sum += (vals.get(i) - ave)*(vals.get(i) - ave);
			}
			double a = sum/n;
			a = Math.sqrt(a);
			System.out.println(String.format("%.5f", 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 while (n != 0) {
			double sum = 0;
			List<Integer> vals = new ArrayList<Integer>();
			for (int i = 0; i < n; i++) {
				int a = sc.nextInt();
				vals.add(a);
				sum += a;
			}
			double ave = sum/n;
			sum = 0;
			for (int i = 0; i < n; i++) {
				sum += (vals.get(i) - ave)*(vals.get(i) - ave);
			}
			double a = sum/n;
			a = Math.sqrt(a);
			System.out.println(String.format("%.5f", a));
			n = sc.nextInt();
		} n != 0 n 0 {
			double sum = 0;
			List<Integer> vals = new ArrayList<Integer>();
			for (int i = 0; i < n; i++) {
				int a = sc.nextInt();
				vals.add(a);
				sum += a;
			}
			double ave = sum/n;
			sum = 0;
			for (int i = 0; i < n; i++) {
				sum += (vals.get(i) - ave)*(vals.get(i) - ave);
			}
			double a = sum/n;
			a = Math.sqrt(a);
			System.out.println(String.format("%.5f", a));
			n = sc.nextInt();
		} double sum = 0; sum 0 List<Integer> vals = new ArrayList<Integer>(); vals new ArrayList<Integer>() for (int i = 0; i < n; i++) {
				int a = sc.nextInt();
				vals.add(a);
				sum += a;
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				int a = sc.nextInt();
				vals.add(a);
				sum += a;
			} {
				int a = sc.nextInt();
				vals.add(a);
				sum += a;
			} int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc vals.add(a) vals.add vals a sum += a sum a double ave = sum/n; ave sum/n sum n sum = 0 sum 0 for (int i = 0; i < n; i++) {
				sum += (vals.get(i) - ave)*(vals.get(i) - ave);
			} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
				sum += (vals.get(i) - ave)*(vals.get(i) - ave);
			} {
				sum += (vals.get(i) - ave)*(vals.get(i) - ave);
			} sum += (vals.get(i) - ave)*(vals.get(i) - ave) sum (vals.get(i) - ave)*(vals.get(i) - ave) (vals.get(i) - ave) vals.get(i) vals.get vals i ave (vals.get(i) - ave) vals.get(i) vals.get vals i ave double a = sum/n; a sum/n sum n a = Math.sqrt(a) a Math.sqrt(a) Math.sqrt Math a System.out.println(String.format("%.5f", a)) System.out.println System.out System System.out String.format("%.5f", a) String.format String "%.5f" a n = sc.nextInt() n sc.nextInt() sc.nextInt sc String[] args args public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		while (n != 0) {
			double sum = 0;
			List<Integer> vals = new ArrayList<Integer>();
			for (int i = 0; i < n; i++) {
				int a = sc.nextInt();
				vals.add(a);
				sum += a;
			}
			double ave = sum/n;
			sum = 0;
			for (int i = 0; i < n; i++) {
				sum += (vals.get(i) - ave)*(vals.get(i) - ave);
			}
			double a = sum/n;
			a = Math.sqrt(a);
			System.out.println(String.format("%.5f", a));
			n = sc.nextInt();
		}
	}
} public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		while (n != 0) {
			double sum = 0;
			List<Integer> vals = new ArrayList<Integer>();
			for (int i = 0; i < n; i++) {
				int a = sc.nextInt();
				vals.add(a);
				sum += a;
			}
			double ave = sum/n;
			sum = 0;
			for (int i = 0; i < n; i++) {
				sum += (vals.get(i) - ave)*(vals.get(i) - ave);
			}
			double a = sum/n;
			a = Math.sqrt(a);
			System.out.println(String.format("%.5f", a));
			n = sc.nextInt();
		}
	}
} Main
import java.util.Scanner;
import java.util.*;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		while (n != 0) {
			double sum = 0;
			List<Integer> vals = new ArrayList<Integer>();
			for (int i = 0; i < n; i++) {
				int a = sc.nextInt();
				vals.add(a);
				sum += a;
			}
			double ave = sum/n;
			sum = 0;
			for (int i = 0; i < n; i++) {
				sum += (vals.get(i) - ave)*(vals.get(i) - ave);
			}
			double a = sum/n;
			a = Math.sqrt(a);
			System.out.println(String.format("%.5f", a));
			n = sc.nextInt();
		}
	}
}

