import java.util.Scanner;

public class Main {

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

        while(true) {
            int n = scanner.nextInt();
            if (n == 0) break;

            int s[] = new int[n];
            for (int i = 0; i < n; i++) {
                s[i] = scanner.nextInt();
            }
            double sum = 0;
            for (int i = 0; i < n; i++) {
                sum += s[i];
            }
            double mean = sum / n;
            double var = 0;
            for (int i = 0; i < n; i++) {
                var += Math.pow((s[i] - mean), 2);
            }
            var = var / n;
            double stddev = Math.sqrt(var);
            System.out.printf("%.8f\n", stddev);
        }
        scanner.close();
    }
}
 import java.util.Scanner; Scanner java.util public class Main {

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

        while(true) {
            int n = scanner.nextInt();
            if (n == 0) break;

            int s[] = new int[n];
            for (int i = 0; i < n; i++) {
                s[i] = scanner.nextInt();
            }
            double sum = 0;
            for (int i = 0; i < n; i++) {
                sum += s[i];
            }
            double mean = sum / n;
            double var = 0;
            for (int i = 0; i < n; i++) {
                var += Math.pow((s[i] - mean), 2);
            }
            var = var / n;
            double stddev = Math.sqrt(var);
            System.out.printf("%.8f\n", stddev);
        }
        scanner.close();
    }
} Main public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        while(true) {
            int n = scanner.nextInt();
            if (n == 0) break;

            int s[] = new int[n];
            for (int i = 0; i < n; i++) {
                s[i] = scanner.nextInt();
            }
            double sum = 0;
            for (int i = 0; i < n; i++) {
                sum += s[i];
            }
            double mean = sum / n;
            double var = 0;
            for (int i = 0; i < n; i++) {
                var += Math.pow((s[i] - mean), 2);
            }
            var = var / n;
            double stddev = Math.sqrt(var);
            System.out.printf("%.8f\n", stddev);
        }
        scanner.close();
    } main {
        Scanner scanner = new Scanner(System.in);

        while(true) {
            int n = scanner.nextInt();
            if (n == 0) break;

            int s[] = new int[n];
            for (int i = 0; i < n; i++) {
                s[i] = scanner.nextInt();
            }
            double sum = 0;
            for (int i = 0; i < n; i++) {
                sum += s[i];
            }
            double mean = sum / n;
            double var = 0;
            for (int i = 0; i < n; i++) {
                var += Math.pow((s[i] - mean), 2);
            }
            var = var / n;
            double stddev = Math.sqrt(var);
            System.out.printf("%.8f\n", stddev);
        }
        scanner.close();
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) while(true) {
            int n = scanner.nextInt();
            if (n == 0) break;

            int s[] = new int[n];
            for (int i = 0; i < n; i++) {
                s[i] = scanner.nextInt();
            }
            double sum = 0;
            for (int i = 0; i < n; i++) {
                sum += s[i];
            }
            double mean = sum / n;
            double var = 0;
            for (int i = 0; i < n; i++) {
                var += Math.pow((s[i] - mean), 2);
            }
            var = var / n;
            double stddev = Math.sqrt(var);
            System.out.printf("%.8f\n", stddev);
        } true {
            int n = scanner.nextInt();
            if (n == 0) break;

            int s[] = new int[n];
            for (int i = 0; i < n; i++) {
                s[i] = scanner.nextInt();
            }
            double sum = 0;
            for (int i = 0; i < n; i++) {
                sum += s[i];
            }
            double mean = sum / n;
            double var = 0;
            for (int i = 0; i < n; i++) {
                var += Math.pow((s[i] - mean), 2);
            }
            var = var / n;
            double stddev = Math.sqrt(var);
            System.out.printf("%.8f\n", stddev);
        } int n = scanner.nextInt(); n scanner.nextInt() scanner.nextInt scanner if (n == 0) break; n == 0 n 0 break; int s[] = new int[n]; s new int[n] n for (int i = 0; i < n; i++) {
                s[i] = scanner.nextInt();
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                s[i] = scanner.nextInt();
            } {
                s[i] = scanner.nextInt();
            } s[i] = scanner.nextInt() s[i] s i scanner.nextInt() scanner.nextInt scanner double sum = 0; sum 0 for (int i = 0; i < n; i++) {
                sum += s[i];
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                sum += s[i];
            } {
                sum += s[i];
            } sum += s[i] sum s[i] s i double mean = sum / n; mean sum / n sum n double var = 0; var 0 for (int i = 0; i < n; i++) {
                var += Math.pow((s[i] - mean), 2);
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                var += Math.pow((s[i] - mean), 2);
            } {
                var += Math.pow((s[i] - mean), 2);
            } var += Math.pow((s[i] - mean), 2) var Math.pow((s[i] - mean), 2) Math.pow Math (s[i] - mean) s[i] s i mean 2 var = var / n var var / n var n double stddev = Math.sqrt(var); stddev Math.sqrt(var) Math.sqrt Math var System.out.printf("%.8f\n", stddev) System.out.printf System.out System System.out "%.8f\n" stddev scanner.close() scanner.close scanner String[] args args public class Main {

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

        while(true) {
            int n = scanner.nextInt();
            if (n == 0) break;

            int s[] = new int[n];
            for (int i = 0; i < n; i++) {
                s[i] = scanner.nextInt();
            }
            double sum = 0;
            for (int i = 0; i < n; i++) {
                sum += s[i];
            }
            double mean = sum / n;
            double var = 0;
            for (int i = 0; i < n; i++) {
                var += Math.pow((s[i] - mean), 2);
            }
            var = var / n;
            double stddev = Math.sqrt(var);
            System.out.printf("%.8f\n", stddev);
        }
        scanner.close();
    }
} public class Main {

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

        while(true) {
            int n = scanner.nextInt();
            if (n == 0) break;

            int s[] = new int[n];
            for (int i = 0; i < n; i++) {
                s[i] = scanner.nextInt();
            }
            double sum = 0;
            for (int i = 0; i < n; i++) {
                sum += s[i];
            }
            double mean = sum / n;
            double var = 0;
            for (int i = 0; i < n; i++) {
                var += Math.pow((s[i] - mean), 2);
            }
            var = var / n;
            double stddev = Math.sqrt(var);
            System.out.printf("%.8f\n", stddev);
        }
        scanner.close();
    }
} Main
import java.util.Scanner;

public class Main {

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

        while(true) {
            int n = scanner.nextInt();
            if (n == 0) break;

            int s[] = new int[n];
            for (int i = 0; i < n; i++) {
                s[i] = scanner.nextInt();
            }
            double sum = 0;
            for (int i = 0; i < n; i++) {
                sum += s[i];
            }
            double mean = sum / n;
            double var = 0;
            for (int i = 0; i < n; i++) {
                var += Math.pow((s[i] - mean), 2);
            }
            var = var / n;
            double stddev = Math.sqrt(var);
            System.out.printf("%.8f\n", stddev);
        }
        scanner.close();
    }
}

