import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while (true) {
            int n = Integer.parseInt(sc.next());
            if (n == 0) break;

            List<Integer> S = new ArrayList<>();
            double ave = 0.0;
            for (int i = 0; i < n; i++) {
                S.add(Integer.parseInt(sc.next()));
                ave += S.get(i);
            }
            ave /= n;

            double ans = 0.0;
            for (int i = 0; i < n; i++) {
                ans += Math.pow((S.get(i) - ave), 2.0);
            }
            ans /= n;

            System.out.println(Math.sqrt(ans));
        }
    }
} import java.util.ArrayList; ArrayList java.util import java.util.List; List java.util import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while (true) {
            int n = Integer.parseInt(sc.next());
            if (n == 0) break;

            List<Integer> S = new ArrayList<>();
            double ave = 0.0;
            for (int i = 0; i < n; i++) {
                S.add(Integer.parseInt(sc.next()));
                ave += S.get(i);
            }
            ave /= n;

            double ans = 0.0;
            for (int i = 0; i < n; i++) {
                ans += Math.pow((S.get(i) - ave), 2.0);
            }
            ans /= n;

            System.out.println(Math.sqrt(ans));
        }
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while (true) {
            int n = Integer.parseInt(sc.next());
            if (n == 0) break;

            List<Integer> S = new ArrayList<>();
            double ave = 0.0;
            for (int i = 0; i < n; i++) {
                S.add(Integer.parseInt(sc.next()));
                ave += S.get(i);
            }
            ave /= n;

            double ans = 0.0;
            for (int i = 0; i < n; i++) {
                ans += Math.pow((S.get(i) - ave), 2.0);
            }
            ans /= n;

            System.out.println(Math.sqrt(ans));
        }
    } main {
        Scanner sc = new Scanner(System.in);

        while (true) {
            int n = Integer.parseInt(sc.next());
            if (n == 0) break;

            List<Integer> S = new ArrayList<>();
            double ave = 0.0;
            for (int i = 0; i < n; i++) {
                S.add(Integer.parseInt(sc.next()));
                ave += S.get(i);
            }
            ave /= n;

            double ans = 0.0;
            for (int i = 0; i < n; i++) {
                ans += Math.pow((S.get(i) - ave), 2.0);
            }
            ans /= n;

            System.out.println(Math.sqrt(ans));
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while (true) {
            int n = Integer.parseInt(sc.next());
            if (n == 0) break;

            List<Integer> S = new ArrayList<>();
            double ave = 0.0;
            for (int i = 0; i < n; i++) {
                S.add(Integer.parseInt(sc.next()));
                ave += S.get(i);
            }
            ave /= n;

            double ans = 0.0;
            for (int i = 0; i < n; i++) {
                ans += Math.pow((S.get(i) - ave), 2.0);
            }
            ans /= n;

            System.out.println(Math.sqrt(ans));
        } true {
            int n = Integer.parseInt(sc.next());
            if (n == 0) break;

            List<Integer> S = new ArrayList<>();
            double ave = 0.0;
            for (int i = 0; i < n; i++) {
                S.add(Integer.parseInt(sc.next()));
                ave += S.get(i);
            }
            ave /= n;

            double ans = 0.0;
            for (int i = 0; i < n; i++) {
                ans += Math.pow((S.get(i) - ave), 2.0);
            }
            ans /= n;

            System.out.println(Math.sqrt(ans));
        } int n = Integer.parseInt(sc.next()); n Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc if (n == 0) break; n == 0 n 0 break; List<Integer> S = new ArrayList<>(); S new ArrayList<>() double ave = 0.0; ave 0.0 for (int i = 0; i < n; i++) {
                S.add(Integer.parseInt(sc.next()));
                ave += S.get(i);
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                S.add(Integer.parseInt(sc.next()));
                ave += S.get(i);
            } {
                S.add(Integer.parseInt(sc.next()));
                ave += S.get(i);
            } S.add(Integer.parseInt(sc.next())) S.add S Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc ave += S.get(i) ave S.get(i) S.get S i ave /= n ave n double ans = 0.0; ans 0.0 for (int i = 0; i < n; i++) {
                ans += Math.pow((S.get(i) - ave), 2.0);
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                ans += Math.pow((S.get(i) - ave), 2.0);
            } {
                ans += Math.pow((S.get(i) - ave), 2.0);
            } ans += Math.pow((S.get(i) - ave), 2.0) ans Math.pow((S.get(i) - ave), 2.0) Math.pow Math (S.get(i) - ave) S.get(i) S.get S i ave 2.0 ans /= n ans n System.out.println(Math.sqrt(ans)) System.out.println System.out System System.out Math.sqrt(ans) Math.sqrt Math ans String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while (true) {
            int n = Integer.parseInt(sc.next());
            if (n == 0) break;

            List<Integer> S = new ArrayList<>();
            double ave = 0.0;
            for (int i = 0; i < n; i++) {
                S.add(Integer.parseInt(sc.next()));
                ave += S.get(i);
            }
            ave /= n;

            double ans = 0.0;
            for (int i = 0; i < n; i++) {
                ans += Math.pow((S.get(i) - ave), 2.0);
            }
            ans /= n;

            System.out.println(Math.sqrt(ans));
        }
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while (true) {
            int n = Integer.parseInt(sc.next());
            if (n == 0) break;

            List<Integer> S = new ArrayList<>();
            double ave = 0.0;
            for (int i = 0; i < n; i++) {
                S.add(Integer.parseInt(sc.next()));
                ave += S.get(i);
            }
            ave /= n;

            double ans = 0.0;
            for (int i = 0; i < n; i++) {
                ans += Math.pow((S.get(i) - ave), 2.0);
            }
            ans /= n;

            System.out.println(Math.sqrt(ans));
        }
    }
} Main
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while (true) {
            int n = Integer.parseInt(sc.next());
            if (n == 0) break;

            List<Integer> S = new ArrayList<>();
            double ave = 0.0;
            for (int i = 0; i < n; i++) {
                S.add(Integer.parseInt(sc.next()));
                ave += S.get(i);
            }
            ave /= n;

            double ans = 0.0;
            for (int i = 0; i < n; i++) {
                ans += Math.pow((S.get(i) - ave), 2.0);
            }
            ans /= n;

            System.out.println(Math.sqrt(ans));
        }
    }
}