import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (true) {
            int n = 0;
            double m = 0,s,s2=0;
            n = sc.nextInt();
            if (n == 0)
                break;
            int[] d = new int[n];
            for (int i = 0; i < n; i++) {
                d[i] = sc.nextInt();
                m += d[i];
            }
            m /= n;
            for (int j = 0; j < n; j++)
                s2 += Math.pow(d[j]-m,2);
            s2 /= n;
            s = Math.sqrt(s2);

            System.out.println(s);
        }
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (true) {
            int n = 0;
            double m = 0,s,s2=0;
            n = sc.nextInt();
            if (n == 0)
                break;
            int[] d = new int[n];
            for (int i = 0; i < n; i++) {
                d[i] = sc.nextInt();
                m += d[i];
            }
            m /= n;
            for (int j = 0; j < n; j++)
                s2 += Math.pow(d[j]-m,2);
            s2 /= n;
            s = Math.sqrt(s2);

            System.out.println(s);
        }
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (true) {
            int n = 0;
            double m = 0,s,s2=0;
            n = sc.nextInt();
            if (n == 0)
                break;
            int[] d = new int[n];
            for (int i = 0; i < n; i++) {
                d[i] = sc.nextInt();
                m += d[i];
            }
            m /= n;
            for (int j = 0; j < n; j++)
                s2 += Math.pow(d[j]-m,2);
            s2 /= n;
            s = Math.sqrt(s2);

            System.out.println(s);
        }
    } main {
        Scanner sc = new Scanner(System.in);
        while (true) {
            int n = 0;
            double m = 0,s,s2=0;
            n = sc.nextInt();
            if (n == 0)
                break;
            int[] d = new int[n];
            for (int i = 0; i < n; i++) {
                d[i] = sc.nextInt();
                m += d[i];
            }
            m /= n;
            for (int j = 0; j < n; j++)
                s2 += Math.pow(d[j]-m,2);
            s2 /= n;
            s = Math.sqrt(s2);

            System.out.println(s);
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while (true) {
            int n = 0;
            double m = 0,s,s2=0;
            n = sc.nextInt();
            if (n == 0)
                break;
            int[] d = new int[n];
            for (int i = 0; i < n; i++) {
                d[i] = sc.nextInt();
                m += d[i];
            }
            m /= n;
            for (int j = 0; j < n; j++)
                s2 += Math.pow(d[j]-m,2);
            s2 /= n;
            s = Math.sqrt(s2);

            System.out.println(s);
        } true {
            int n = 0;
            double m = 0,s,s2=0;
            n = sc.nextInt();
            if (n == 0)
                break;
            int[] d = new int[n];
            for (int i = 0; i < n; i++) {
                d[i] = sc.nextInt();
                m += d[i];
            }
            m /= n;
            for (int j = 0; j < n; j++)
                s2 += Math.pow(d[j]-m,2);
            s2 /= n;
            s = Math.sqrt(s2);

            System.out.println(s);
        } int n = 0; n 0 double m = 0 m 0 s s s2=0; s2 0 n = sc.nextInt() n sc.nextInt() sc.nextInt sc if (n == 0)
                break; n == 0 n 0 break; int[] d = new int[n]; d new int[n] n for (int i = 0; i < n; i++) {
                d[i] = sc.nextInt();
                m += d[i];
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                d[i] = sc.nextInt();
                m += d[i];
            } {
                d[i] = sc.nextInt();
                m += d[i];
            } d[i] = sc.nextInt() d[i] d i sc.nextInt() sc.nextInt sc m += d[i] m d[i] d i m /= n m n for (int j = 0; j < n; j++)
                s2 += Math.pow(d[j]-m,2); int j = 0; int j = 0; j 0 j < n j n j++ j++ j s2 += Math.pow(d[j]-m,2); s2 += Math.pow(d[j]-m,2) s2 Math.pow(d[j]-m,2) Math.pow Math d[j]-m d[j] d j m 2 s2 /= n s2 n s = Math.sqrt(s2) s Math.sqrt(s2) Math.sqrt Math s2 System.out.println(s) System.out.println System.out System System.out s String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (true) {
            int n = 0;
            double m = 0,s,s2=0;
            n = sc.nextInt();
            if (n == 0)
                break;
            int[] d = new int[n];
            for (int i = 0; i < n; i++) {
                d[i] = sc.nextInt();
                m += d[i];
            }
            m /= n;
            for (int j = 0; j < n; j++)
                s2 += Math.pow(d[j]-m,2);
            s2 /= n;
            s = Math.sqrt(s2);

            System.out.println(s);
        }
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (true) {
            int n = 0;
            double m = 0,s,s2=0;
            n = sc.nextInt();
            if (n == 0)
                break;
            int[] d = new int[n];
            for (int i = 0; i < n; i++) {
                d[i] = sc.nextInt();
                m += d[i];
            }
            m /= n;
            for (int j = 0; j < n; j++)
                s2 += Math.pow(d[j]-m,2);
            s2 /= n;
            s = Math.sqrt(s2);

            System.out.println(s);
        }
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (true) {
            int n = 0;
            double m = 0,s,s2=0;
            n = sc.nextInt();
            if (n == 0)
                break;
            int[] d = new int[n];
            for (int i = 0; i < n; i++) {
                d[i] = sc.nextInt();
                m += d[i];
            }
            m /= n;
            for (int j = 0; j < n; j++)
                s2 += Math.pow(d[j]-m,2);
            s2 /= n;
            s = Math.sqrt(s2);

            System.out.println(s);
        }
    }
}
