import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        double a = 0.0;

        while (true) {
            int n = scan.nextInt();
            int sum = 0;
            int[] students = new int[n];
            if (n == 0) break;

            for (int i = 0; i < n; i++) {
                int s = scan.nextInt();
                students[i] = s;
                sum += s;
            }
            double m = (double)sum / n;
            double sum2 = 0.0;
            for (int i = 0; i < n; i++) {
                sum2 += Math.pow(students[i] - m, 2);
            }
            a = Math.sqrt(sum2 / n);
            System.out.println(a);
        }
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        double a = 0.0;

        while (true) {
            int n = scan.nextInt();
            int sum = 0;
            int[] students = new int[n];
            if (n == 0) break;

            for (int i = 0; i < n; i++) {
                int s = scan.nextInt();
                students[i] = s;
                sum += s;
            }
            double m = (double)sum / n;
            double sum2 = 0.0;
            for (int i = 0; i < n; i++) {
                sum2 += Math.pow(students[i] - m, 2);
            }
            a = Math.sqrt(sum2 / n);
            System.out.println(a);
        }
    }
} Main public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        double a = 0.0;

        while (true) {
            int n = scan.nextInt();
            int sum = 0;
            int[] students = new int[n];
            if (n == 0) break;

            for (int i = 0; i < n; i++) {
                int s = scan.nextInt();
                students[i] = s;
                sum += s;
            }
            double m = (double)sum / n;
            double sum2 = 0.0;
            for (int i = 0; i < n; i++) {
                sum2 += Math.pow(students[i] - m, 2);
            }
            a = Math.sqrt(sum2 / n);
            System.out.println(a);
        }
    } main {
        Scanner scan = new Scanner(System.in);
        double a = 0.0;

        while (true) {
            int n = scan.nextInt();
            int sum = 0;
            int[] students = new int[n];
            if (n == 0) break;

            for (int i = 0; i < n; i++) {
                int s = scan.nextInt();
                students[i] = s;
                sum += s;
            }
            double m = (double)sum / n;
            double sum2 = 0.0;
            for (int i = 0; i < n; i++) {
                sum2 += Math.pow(students[i] - m, 2);
            }
            a = Math.sqrt(sum2 / n);
            System.out.println(a);
        }
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) double a = 0.0; a 0.0 while (true) {
            int n = scan.nextInt();
            int sum = 0;
            int[] students = new int[n];
            if (n == 0) break;

            for (int i = 0; i < n; i++) {
                int s = scan.nextInt();
                students[i] = s;
                sum += s;
            }
            double m = (double)sum / n;
            double sum2 = 0.0;
            for (int i = 0; i < n; i++) {
                sum2 += Math.pow(students[i] - m, 2);
            }
            a = Math.sqrt(sum2 / n);
            System.out.println(a);
        } true {
            int n = scan.nextInt();
            int sum = 0;
            int[] students = new int[n];
            if (n == 0) break;

            for (int i = 0; i < n; i++) {
                int s = scan.nextInt();
                students[i] = s;
                sum += s;
            }
            double m = (double)sum / n;
            double sum2 = 0.0;
            for (int i = 0; i < n; i++) {
                sum2 += Math.pow(students[i] - m, 2);
            }
            a = Math.sqrt(sum2 / n);
            System.out.println(a);
        } int n = scan.nextInt(); n scan.nextInt() scan.nextInt scan int sum = 0; sum 0 int[] students = new int[n]; students new int[n] n if (n == 0) break; n == 0 n 0 break; for (int i = 0; i < n; i++) {
                int s = scan.nextInt();
                students[i] = s;
                sum += s;
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                int s = scan.nextInt();
                students[i] = s;
                sum += s;
            } {
                int s = scan.nextInt();
                students[i] = s;
                sum += s;
            } int s = scan.nextInt(); s scan.nextInt() scan.nextInt scan students[i] = s students[i] students i s sum += s sum s double m = (double)sum / n; m (double)sum / n (double)sum n double sum2 = 0.0; sum2 0.0 for (int i = 0; i < n; i++) {
                sum2 += Math.pow(students[i] - m, 2);
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                sum2 += Math.pow(students[i] - m, 2);
            } {
                sum2 += Math.pow(students[i] - m, 2);
            } sum2 += Math.pow(students[i] - m, 2) sum2 Math.pow(students[i] - m, 2) Math.pow Math students[i] - m students[i] students i m 2 a = Math.sqrt(sum2 / n) a Math.sqrt(sum2 / n) Math.sqrt Math sum2 / n sum2 n 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) {
        Scanner scan = new Scanner(System.in);
        double a = 0.0;

        while (true) {
            int n = scan.nextInt();
            int sum = 0;
            int[] students = new int[n];
            if (n == 0) break;

            for (int i = 0; i < n; i++) {
                int s = scan.nextInt();
                students[i] = s;
                sum += s;
            }
            double m = (double)sum / n;
            double sum2 = 0.0;
            for (int i = 0; i < n; i++) {
                sum2 += Math.pow(students[i] - m, 2);
            }
            a = Math.sqrt(sum2 / n);
            System.out.println(a);
        }
    }
} public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        double a = 0.0;

        while (true) {
            int n = scan.nextInt();
            int sum = 0;
            int[] students = new int[n];
            if (n == 0) break;

            for (int i = 0; i < n; i++) {
                int s = scan.nextInt();
                students[i] = s;
                sum += s;
            }
            double m = (double)sum / n;
            double sum2 = 0.0;
            for (int i = 0; i < n; i++) {
                sum2 += Math.pow(students[i] - m, 2);
            }
            a = Math.sqrt(sum2 / n);
            System.out.println(a);
        }
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        double a = 0.0;

        while (true) {
            int n = scan.nextInt();
            int sum = 0;
            int[] students = new int[n];
            if (n == 0) break;

            for (int i = 0; i < n; i++) {
                int s = scan.nextInt();
                students[i] = s;
                sum += s;
            }
            double m = (double)sum / n;
            double sum2 = 0.0;
            for (int i = 0; i < n; i++) {
                sum2 += Math.pow(students[i] - m, 2);
            }
            a = Math.sqrt(sum2 / n);
            System.out.println(a);
        }
    }
}