import java.util.*;

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

        int n, i, sum = 0;
        double average, a = 0;
        int data[] = new int[1001];

        while((n = scan.nextInt()) != 0) {
            for(i = 0; i < n; i++) {
                data[i] = scan.nextInt();
                sum += data[i];
            }
            data[n] = '\0';
            average = (double)sum / n;
            for(i = 0; i < n; i++) {
                a += Math.pow(data[i] - average, 2);
            }
            System.out.printf("%.8f\n", Math.sqrt(a / n));
            sum = 0;
            a = 0;
        }
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        int n, i, sum = 0;
        double average, a = 0;
        int data[] = new int[1001];

        while((n = scan.nextInt()) != 0) {
            for(i = 0; i < n; i++) {
                data[i] = scan.nextInt();
                sum += data[i];
            }
            data[n] = '\0';
            average = (double)sum / n;
            for(i = 0; i < n; i++) {
                a += Math.pow(data[i] - average, 2);
            }
            System.out.printf("%.8f\n", Math.sqrt(a / n));
            sum = 0;
            a = 0;
        }
    }
} Main public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        int n, i, sum = 0;
        double average, a = 0;
        int data[] = new int[1001];

        while((n = scan.nextInt()) != 0) {
            for(i = 0; i < n; i++) {
                data[i] = scan.nextInt();
                sum += data[i];
            }
            data[n] = '\0';
            average = (double)sum / n;
            for(i = 0; i < n; i++) {
                a += Math.pow(data[i] - average, 2);
            }
            System.out.printf("%.8f\n", Math.sqrt(a / n));
            sum = 0;
            a = 0;
        }
    } main {
        Scanner scan = new Scanner(System.in);

        int n, i, sum = 0;
        double average, a = 0;
        int data[] = new int[1001];

        while((n = scan.nextInt()) != 0) {
            for(i = 0; i < n; i++) {
                data[i] = scan.nextInt();
                sum += data[i];
            }
            data[n] = '\0';
            average = (double)sum / n;
            for(i = 0; i < n; i++) {
                a += Math.pow(data[i] - average, 2);
            }
            System.out.printf("%.8f\n", Math.sqrt(a / n));
            sum = 0;
            a = 0;
        }
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int n n i i sum = 0; sum 0 double average average a = 0; a 0 int data[] = new int[1001]; data new int[1001] 1001 while((n = scan.nextInt()) != 0) {
            for(i = 0; i < n; i++) {
                data[i] = scan.nextInt();
                sum += data[i];
            }
            data[n] = '\0';
            average = (double)sum / n;
            for(i = 0; i < n; i++) {
                a += Math.pow(data[i] - average, 2);
            }
            System.out.printf("%.8f\n", Math.sqrt(a / n));
            sum = 0;
            a = 0;
        } (n = scan.nextInt()) != 0 (n = scan.nextInt()) n scan.nextInt() scan.nextInt scan 0 {
            for(i = 0; i < n; i++) {
                data[i] = scan.nextInt();
                sum += data[i];
            }
            data[n] = '\0';
            average = (double)sum / n;
            for(i = 0; i < n; i++) {
                a += Math.pow(data[i] - average, 2);
            }
            System.out.printf("%.8f\n", Math.sqrt(a / n));
            sum = 0;
            a = 0;
        } for(i = 0; i < n; i++) {
                data[i] = scan.nextInt();
                sum += data[i];
            } i = 0; i = 0 i 0 i < n i n i++ i++ i {
                data[i] = scan.nextInt();
                sum += data[i];
            } {
                data[i] = scan.nextInt();
                sum += data[i];
            } data[i] = scan.nextInt() data[i] data i scan.nextInt() scan.nextInt scan sum += data[i] sum data[i] data i data[n] = '\0' data[n] data n '\0' average = (double)sum / n average (double)sum / n (double)sum n for(i = 0; i < n; i++) {
                a += Math.pow(data[i] - average, 2);
            } i = 0; i = 0 i 0 i < n i n i++ i++ i {
                a += Math.pow(data[i] - average, 2);
            } {
                a += Math.pow(data[i] - average, 2);
            } a += Math.pow(data[i] - average, 2) a Math.pow(data[i] - average, 2) Math.pow Math data[i] - average data[i] data i average 2 System.out.printf("%.8f\n", Math.sqrt(a / n)) System.out.printf System.out System System.out "%.8f\n" Math.sqrt(a / n) Math.sqrt Math a / n a n sum = 0 sum 0 a = 0 a 0 String[] args args public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        int n, i, sum = 0;
        double average, a = 0;
        int data[] = new int[1001];

        while((n = scan.nextInt()) != 0) {
            for(i = 0; i < n; i++) {
                data[i] = scan.nextInt();
                sum += data[i];
            }
            data[n] = '\0';
            average = (double)sum / n;
            for(i = 0; i < n; i++) {
                a += Math.pow(data[i] - average, 2);
            }
            System.out.printf("%.8f\n", Math.sqrt(a / n));
            sum = 0;
            a = 0;
        }
    }
} public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        int n, i, sum = 0;
        double average, a = 0;
        int data[] = new int[1001];

        while((n = scan.nextInt()) != 0) {
            for(i = 0; i < n; i++) {
                data[i] = scan.nextInt();
                sum += data[i];
            }
            data[n] = '\0';
            average = (double)sum / n;
            for(i = 0; i < n; i++) {
                a += Math.pow(data[i] - average, 2);
            }
            System.out.printf("%.8f\n", Math.sqrt(a / n));
            sum = 0;
            a = 0;
        }
    }
} Main
import java.util.*;

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

        int n, i, sum = 0;
        double average, a = 0;
        int data[] = new int[1001];

        while((n = scan.nextInt()) != 0) {
            for(i = 0; i < n; i++) {
                data[i] = scan.nextInt();
                sum += data[i];
            }
            data[n] = '\0';
            average = (double)sum / n;
            for(i = 0; i < n; i++) {
                a += Math.pow(data[i] - average, 2);
            }
            System.out.printf("%.8f\n", Math.sqrt(a / n));
            sum = 0;
            a = 0;
        }
    }
}
