import java.util.*;

public class Main {
    
    public static void main(String[] args) {
        Main main = new Main();
        main.solv();
    }
    
    private void solv() {
        Scanner input = new Scanner(System.in);
        while (true) {
            int n = input.nextInt();
            if (n == 0) break;
            List<Integer> list = new ArrayList<Integer>();
            int sum = 0;
            for (int i = 0; i < n; i++) {
                int s = input.nextInt();
                list.add(s);
                sum += s;
            }
            double avg = (double)sum / list.size();
            double a = 0;
            for (int s : list) {
                a += Math.pow(s - avg, 2);
            }
            System.out.println(Math.sqrt(a / list.size()));
        }
    }
} import java.util.*; util.* java public class Main {
    
    public static void main(String[] args) {
        Main main = new Main();
        main.solv();
    }
    
    private void solv() {
        Scanner input = new Scanner(System.in);
        while (true) {
            int n = input.nextInt();
            if (n == 0) break;
            List<Integer> list = new ArrayList<Integer>();
            int sum = 0;
            for (int i = 0; i < n; i++) {
                int s = input.nextInt();
                list.add(s);
                sum += s;
            }
            double avg = (double)sum / list.size();
            double a = 0;
            for (int s : list) {
                a += Math.pow(s - avg, 2);
            }
            System.out.println(Math.sqrt(a / list.size()));
        }
    }
} Main public static void main(String[] args) {
        Main main = new Main();
        main.solv();
    } main {
        Main main = new Main();
        main.solv();
    } Main main = new Main(); main new Main() main.solv() main.solv main String[] args args private void solv() {
        Scanner input = new Scanner(System.in);
        while (true) {
            int n = input.nextInt();
            if (n == 0) break;
            List<Integer> list = new ArrayList<Integer>();
            int sum = 0;
            for (int i = 0; i < n; i++) {
                int s = input.nextInt();
                list.add(s);
                sum += s;
            }
            double avg = (double)sum / list.size();
            double a = 0;
            for (int s : list) {
                a += Math.pow(s - avg, 2);
            }
            System.out.println(Math.sqrt(a / list.size()));
        }
    } solv {
        Scanner input = new Scanner(System.in);
        while (true) {
            int n = input.nextInt();
            if (n == 0) break;
            List<Integer> list = new ArrayList<Integer>();
            int sum = 0;
            for (int i = 0; i < n; i++) {
                int s = input.nextInt();
                list.add(s);
                sum += s;
            }
            double avg = (double)sum / list.size();
            double a = 0;
            for (int s : list) {
                a += Math.pow(s - avg, 2);
            }
            System.out.println(Math.sqrt(a / list.size()));
        }
    } Scanner input = new Scanner(System.in); input new Scanner(System.in) while (true) {
            int n = input.nextInt();
            if (n == 0) break;
            List<Integer> list = new ArrayList<Integer>();
            int sum = 0;
            for (int i = 0; i < n; i++) {
                int s = input.nextInt();
                list.add(s);
                sum += s;
            }
            double avg = (double)sum / list.size();
            double a = 0;
            for (int s : list) {
                a += Math.pow(s - avg, 2);
            }
            System.out.println(Math.sqrt(a / list.size()));
        } true {
            int n = input.nextInt();
            if (n == 0) break;
            List<Integer> list = new ArrayList<Integer>();
            int sum = 0;
            for (int i = 0; i < n; i++) {
                int s = input.nextInt();
                list.add(s);
                sum += s;
            }
            double avg = (double)sum / list.size();
            double a = 0;
            for (int s : list) {
                a += Math.pow(s - avg, 2);
            }
            System.out.println(Math.sqrt(a / list.size()));
        } int n = input.nextInt(); n input.nextInt() input.nextInt input if (n == 0) break; n == 0 n 0 break; List<Integer> list = new ArrayList<Integer>(); list new ArrayList<Integer>() int sum = 0; sum 0 for (int i = 0; i < n; i++) {
                int s = input.nextInt();
                list.add(s);
                sum += s;
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                int s = input.nextInt();
                list.add(s);
                sum += s;
            } {
                int s = input.nextInt();
                list.add(s);
                sum += s;
            } int s = input.nextInt(); s input.nextInt() input.nextInt input list.add(s) list.add list s sum += s sum s double avg = (double)sum / list.size(); avg (double)sum / list.size() (double)sum list.size() list.size list double a = 0; a 0 for (int s : list) {
                a += Math.pow(s - avg, 2);
            } int s list {
                a += Math.pow(s - avg, 2);
            } {
                a += Math.pow(s - avg, 2);
            } a += Math.pow(s - avg, 2) a Math.pow(s - avg, 2) Math.pow Math s - avg s avg 2 System.out.println(Math.sqrt(a / list.size())) System.out.println System.out System System.out Math.sqrt(a / list.size()) Math.sqrt Math a / list.size() a list.size() list.size list public class Main {
    
    public static void main(String[] args) {
        Main main = new Main();
        main.solv();
    }
    
    private void solv() {
        Scanner input = new Scanner(System.in);
        while (true) {
            int n = input.nextInt();
            if (n == 0) break;
            List<Integer> list = new ArrayList<Integer>();
            int sum = 0;
            for (int i = 0; i < n; i++) {
                int s = input.nextInt();
                list.add(s);
                sum += s;
            }
            double avg = (double)sum / list.size();
            double a = 0;
            for (int s : list) {
                a += Math.pow(s - avg, 2);
            }
            System.out.println(Math.sqrt(a / list.size()));
        }
    }
} public class Main {
    
    public static void main(String[] args) {
        Main main = new Main();
        main.solv();
    }
    
    private void solv() {
        Scanner input = new Scanner(System.in);
        while (true) {
            int n = input.nextInt();
            if (n == 0) break;
            List<Integer> list = new ArrayList<Integer>();
            int sum = 0;
            for (int i = 0; i < n; i++) {
                int s = input.nextInt();
                list.add(s);
                sum += s;
            }
            double avg = (double)sum / list.size();
            double a = 0;
            for (int s : list) {
                a += Math.pow(s - avg, 2);
            }
            System.out.println(Math.sqrt(a / list.size()));
        }
    }
} Main
import java.util.*;

public class Main {
    
    public static void main(String[] args) {
        Main main = new Main();
        main.solv();
    }
    
    private void solv() {
        Scanner input = new Scanner(System.in);
        while (true) {
            int n = input.nextInt();
            if (n == 0) break;
            List<Integer> list = new ArrayList<Integer>();
            int sum = 0;
            for (int i = 0; i < n; i++) {
                int s = input.nextInt();
                list.add(s);
                sum += s;
            }
            double avg = (double)sum / list.size();
            double a = 0;
            for (int s : list) {
                a += Math.pow(s - avg, 2);
            }
            System.out.println(Math.sqrt(a / list.size()));
        }
    }
}