import java.util.Scanner;

public class Main {
    public static void main(String[] args ) {
        Scanner scanner = new Scanner(System.in);
        int[] a = new int[1000];

        int n = scanner.nextInt();
        while(n != 0) {
            double ave = 0;
            for (int i = 0; i < n; i++) {
                a[i] = scanner.nextInt();
                ave += a[i];
            }
            ave /= n;
            double S = 0;
            for (int i = 0; i < n; i++)
                S += (a[i] - ave) * (a[i] - ave);
            System.out.println(Math.sqrt(S / n));
            n = scanner.nextInt();
        }
    }
}
 import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args ) {
        Scanner scanner = new Scanner(System.in);
        int[] a = new int[1000];

        int n = scanner.nextInt();
        while(n != 0) {
            double ave = 0;
            for (int i = 0; i < n; i++) {
                a[i] = scanner.nextInt();
                ave += a[i];
            }
            ave /= n;
            double S = 0;
            for (int i = 0; i < n; i++)
                S += (a[i] - ave) * (a[i] - ave);
            System.out.println(Math.sqrt(S / n));
            n = scanner.nextInt();
        }
    }
} Main public static void main(String[] args ) {
        Scanner scanner = new Scanner(System.in);
        int[] a = new int[1000];

        int n = scanner.nextInt();
        while(n != 0) {
            double ave = 0;
            for (int i = 0; i < n; i++) {
                a[i] = scanner.nextInt();
                ave += a[i];
            }
            ave /= n;
            double S = 0;
            for (int i = 0; i < n; i++)
                S += (a[i] - ave) * (a[i] - ave);
            System.out.println(Math.sqrt(S / n));
            n = scanner.nextInt();
        }
    } main {
        Scanner scanner = new Scanner(System.in);
        int[] a = new int[1000];

        int n = scanner.nextInt();
        while(n != 0) {
            double ave = 0;
            for (int i = 0; i < n; i++) {
                a[i] = scanner.nextInt();
                ave += a[i];
            }
            ave /= n;
            double S = 0;
            for (int i = 0; i < n; i++)
                S += (a[i] - ave) * (a[i] - ave);
            System.out.println(Math.sqrt(S / n));
            n = scanner.nextInt();
        }
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int[] a = new int[1000]; a new int[1000] 1000 int n = scanner.nextInt(); n scanner.nextInt() scanner.nextInt scanner while(n != 0) {
            double ave = 0;
            for (int i = 0; i < n; i++) {
                a[i] = scanner.nextInt();
                ave += a[i];
            }
            ave /= n;
            double S = 0;
            for (int i = 0; i < n; i++)
                S += (a[i] - ave) * (a[i] - ave);
            System.out.println(Math.sqrt(S / n));
            n = scanner.nextInt();
        } n != 0 n 0 {
            double ave = 0;
            for (int i = 0; i < n; i++) {
                a[i] = scanner.nextInt();
                ave += a[i];
            }
            ave /= n;
            double S = 0;
            for (int i = 0; i < n; i++)
                S += (a[i] - ave) * (a[i] - ave);
            System.out.println(Math.sqrt(S / n));
            n = scanner.nextInt();
        } double ave = 0; ave 0 for (int i = 0; i < n; i++) {
                a[i] = scanner.nextInt();
                ave += a[i];
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                a[i] = scanner.nextInt();
                ave += a[i];
            } {
                a[i] = scanner.nextInt();
                ave += a[i];
            } a[i] = scanner.nextInt() a[i] a i scanner.nextInt() scanner.nextInt scanner ave += a[i] ave a[i] a i ave /= n ave n double S = 0; S 0 for (int i = 0; i < n; i++)
                S += (a[i] - ave) * (a[i] - ave); int i = 0; int i = 0; i 0 i < n i n i++ i++ i S += (a[i] - ave) * (a[i] - ave); S += (a[i] - ave) * (a[i] - ave) S (a[i] - ave) * (a[i] - ave) (a[i] - ave) a[i] a i ave (a[i] - ave) a[i] a i ave System.out.println(Math.sqrt(S / n)) System.out.println System.out System System.out Math.sqrt(S / n) Math.sqrt Math S / n S n n = scanner.nextInt() n scanner.nextInt() scanner.nextInt scanner String[] args args public class Main {
    public static void main(String[] args ) {
        Scanner scanner = new Scanner(System.in);
        int[] a = new int[1000];

        int n = scanner.nextInt();
        while(n != 0) {
            double ave = 0;
            for (int i = 0; i < n; i++) {
                a[i] = scanner.nextInt();
                ave += a[i];
            }
            ave /= n;
            double S = 0;
            for (int i = 0; i < n; i++)
                S += (a[i] - ave) * (a[i] - ave);
            System.out.println(Math.sqrt(S / n));
            n = scanner.nextInt();
        }
    }
} public class Main {
    public static void main(String[] args ) {
        Scanner scanner = new Scanner(System.in);
        int[] a = new int[1000];

        int n = scanner.nextInt();
        while(n != 0) {
            double ave = 0;
            for (int i = 0; i < n; i++) {
                a[i] = scanner.nextInt();
                ave += a[i];
            }
            ave /= n;
            double S = 0;
            for (int i = 0; i < n; i++)
                S += (a[i] - ave) * (a[i] - ave);
            System.out.println(Math.sqrt(S / n));
            n = scanner.nextInt();
        }
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args ) {
        Scanner scanner = new Scanner(System.in);
        int[] a = new int[1000];

        int n = scanner.nextInt();
        while(n != 0) {
            double ave = 0;
            for (int i = 0; i < n; i++) {
                a[i] = scanner.nextInt();
                ave += a[i];
            }
            ave /= n;
            double S = 0;
            for (int i = 0; i < n; i++)
                S += (a[i] - ave) * (a[i] - ave);
            System.out.println(Math.sqrt(S / n));
            n = scanner.nextInt();
        }
    }
}

