import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n;
        while ((n = scanner.nextInt()) != 0) {
            int data[] = new int[n];
            for (int i = 0; i < n; i++) {
                data[i] = scanner.nextInt();
            }
    
            int sum = 0;
            for (int i = 0; i < n; i++) {
                sum += data[i];
            }
            double m = (double)sum / n;
            double a2 = 0;
            for (int i = 0; i < n; i++) {
                double d = data[i] - m;
                a2 += d*d;
            }
            a2 /= n;
            double a = Math.sqrt(a2);
            System.out.println(a);
        }
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n;
        while ((n = scanner.nextInt()) != 0) {
            int data[] = new int[n];
            for (int i = 0; i < n; i++) {
                data[i] = scanner.nextInt();
            }
    
            int sum = 0;
            for (int i = 0; i < n; i++) {
                sum += data[i];
            }
            double m = (double)sum / n;
            double a2 = 0;
            for (int i = 0; i < n; i++) {
                double d = data[i] - m;
                a2 += d*d;
            }
            a2 /= n;
            double a = Math.sqrt(a2);
            System.out.println(a);
        }
    }
} Main public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n;
        while ((n = scanner.nextInt()) != 0) {
            int data[] = new int[n];
            for (int i = 0; i < n; i++) {
                data[i] = scanner.nextInt();
            }
    
            int sum = 0;
            for (int i = 0; i < n; i++) {
                sum += data[i];
            }
            double m = (double)sum / n;
            double a2 = 0;
            for (int i = 0; i < n; i++) {
                double d = data[i] - m;
                a2 += d*d;
            }
            a2 /= n;
            double a = Math.sqrt(a2);
            System.out.println(a);
        }
    } main {
        Scanner scanner = new Scanner(System.in);
        int n;
        while ((n = scanner.nextInt()) != 0) {
            int data[] = new int[n];
            for (int i = 0; i < n; i++) {
                data[i] = scanner.nextInt();
            }
    
            int sum = 0;
            for (int i = 0; i < n; i++) {
                sum += data[i];
            }
            double m = (double)sum / n;
            double a2 = 0;
            for (int i = 0; i < n; i++) {
                double d = data[i] - m;
                a2 += d*d;
            }
            a2 /= n;
            double a = Math.sqrt(a2);
            System.out.println(a);
        }
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int n; n while ((n = scanner.nextInt()) != 0) {
            int data[] = new int[n];
            for (int i = 0; i < n; i++) {
                data[i] = scanner.nextInt();
            }
    
            int sum = 0;
            for (int i = 0; i < n; i++) {
                sum += data[i];
            }
            double m = (double)sum / n;
            double a2 = 0;
            for (int i = 0; i < n; i++) {
                double d = data[i] - m;
                a2 += d*d;
            }
            a2 /= n;
            double a = Math.sqrt(a2);
            System.out.println(a);
        } (n = scanner.nextInt()) != 0 (n = scanner.nextInt()) n scanner.nextInt() scanner.nextInt scanner 0 {
            int data[] = new int[n];
            for (int i = 0; i < n; i++) {
                data[i] = scanner.nextInt();
            }
    
            int sum = 0;
            for (int i = 0; i < n; i++) {
                sum += data[i];
            }
            double m = (double)sum / n;
            double a2 = 0;
            for (int i = 0; i < n; i++) {
                double d = data[i] - m;
                a2 += d*d;
            }
            a2 /= n;
            double a = Math.sqrt(a2);
            System.out.println(a);
        } int data[] = new int[n]; data new int[n] n for (int i = 0; i < n; i++) {
                data[i] = scanner.nextInt();
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                data[i] = scanner.nextInt();
            } {
                data[i] = scanner.nextInt();
            } data[i] = scanner.nextInt() data[i] data i scanner.nextInt() scanner.nextInt scanner int sum = 0; sum 0 for (int i = 0; i < n; i++) {
                sum += data[i];
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                sum += data[i];
            } {
                sum += data[i];
            } sum += data[i] sum data[i] data i double m = (double)sum / n; m (double)sum / n (double)sum n double a2 = 0; a2 0 for (int i = 0; i < n; i++) {
                double d = data[i] - m;
                a2 += d*d;
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                double d = data[i] - m;
                a2 += d*d;
            } {
                double d = data[i] - m;
                a2 += d*d;
            } double d = data[i] - m; d data[i] - m data[i] data i m a2 += d*d a2 d*d d d a2 /= n a2 n double a = Math.sqrt(a2); a Math.sqrt(a2) Math.sqrt Math a2 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 scanner = new Scanner(System.in);
        int n;
        while ((n = scanner.nextInt()) != 0) {
            int data[] = new int[n];
            for (int i = 0; i < n; i++) {
                data[i] = scanner.nextInt();
            }
    
            int sum = 0;
            for (int i = 0; i < n; i++) {
                sum += data[i];
            }
            double m = (double)sum / n;
            double a2 = 0;
            for (int i = 0; i < n; i++) {
                double d = data[i] - m;
                a2 += d*d;
            }
            a2 /= n;
            double a = Math.sqrt(a2);
            System.out.println(a);
        }
    }
} public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n;
        while ((n = scanner.nextInt()) != 0) {
            int data[] = new int[n];
            for (int i = 0; i < n; i++) {
                data[i] = scanner.nextInt();
            }
    
            int sum = 0;
            for (int i = 0; i < n; i++) {
                sum += data[i];
            }
            double m = (double)sum / n;
            double a2 = 0;
            for (int i = 0; i < n; i++) {
                double d = data[i] - m;
                a2 += d*d;
            }
            a2 /= n;
            double a = Math.sqrt(a2);
            System.out.println(a);
        }
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n;
        while ((n = scanner.nextInt()) != 0) {
            int data[] = new int[n];
            for (int i = 0; i < n; i++) {
                data[i] = scanner.nextInt();
            }
    
            int sum = 0;
            for (int i = 0; i < n; i++) {
                sum += data[i];
            }
            double m = (double)sum / n;
            double a2 = 0;
            for (int i = 0; i < n; i++) {
                double d = data[i] - m;
                a2 += d*d;
            }
            a2 /= n;
            double a = Math.sqrt(a2);
            System.out.println(a);
        }
    }
}
