import java.io.*;

class Main {
    public static void main (String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n;
        String[] points;
        int[] s;
        int i;
        double m;
        double a;

        while ((n = Integer.parseInt(br.readLine())) != 0) {
            points = br.readLine().split(" ");
            s = new int[n];

            m = 0;
            for (i = 0; i < n; i++) {
                s[i] = Integer.parseInt(points[i]);
                m += s[i];
            }
            m /= n;

            a = 0;
            for (i = 0; i < n; i++) {
                a += Math.pow(s[i] - m, 2);
            }

            System.out.println(Math.sqrt(a / n));
        }

    }
} import java.io.*; io.* java class Main {
    public static void main (String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n;
        String[] points;
        int[] s;
        int i;
        double m;
        double a;

        while ((n = Integer.parseInt(br.readLine())) != 0) {
            points = br.readLine().split(" ");
            s = new int[n];

            m = 0;
            for (i = 0; i < n; i++) {
                s[i] = Integer.parseInt(points[i]);
                m += s[i];
            }
            m /= n;

            a = 0;
            for (i = 0; i < n; i++) {
                a += Math.pow(s[i] - m, 2);
            }

            System.out.println(Math.sqrt(a / n));
        }

    }
} Main public static void main (String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n;
        String[] points;
        int[] s;
        int i;
        double m;
        double a;

        while ((n = Integer.parseInt(br.readLine())) != 0) {
            points = br.readLine().split(" ");
            s = new int[n];

            m = 0;
            for (i = 0; i < n; i++) {
                s[i] = Integer.parseInt(points[i]);
                m += s[i];
            }
            m /= n;

            a = 0;
            for (i = 0; i < n; i++) {
                a += Math.pow(s[i] - m, 2);
            }

            System.out.println(Math.sqrt(a / n));
        }

    } main {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n;
        String[] points;
        int[] s;
        int i;
        double m;
        double a;

        while ((n = Integer.parseInt(br.readLine())) != 0) {
            points = br.readLine().split(" ");
            s = new int[n];

            m = 0;
            for (i = 0; i < n; i++) {
                s[i] = Integer.parseInt(points[i]);
                m += s[i];
            }
            m /= n;

            a = 0;
            for (i = 0; i < n; i++) {
                a += Math.pow(s[i] - m, 2);
            }

            System.out.println(Math.sqrt(a / n));
        }

    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int n; n String[] points; points int[] s; s int i; i double m; m double a; a while ((n = Integer.parseInt(br.readLine())) != 0) {
            points = br.readLine().split(" ");
            s = new int[n];

            m = 0;
            for (i = 0; i < n; i++) {
                s[i] = Integer.parseInt(points[i]);
                m += s[i];
            }
            m /= n;

            a = 0;
            for (i = 0; i < n; i++) {
                a += Math.pow(s[i] - m, 2);
            }

            System.out.println(Math.sqrt(a / n));
        } (n = Integer.parseInt(br.readLine())) != 0 (n = Integer.parseInt(br.readLine())) n Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br 0 {
            points = br.readLine().split(" ");
            s = new int[n];

            m = 0;
            for (i = 0; i < n; i++) {
                s[i] = Integer.parseInt(points[i]);
                m += s[i];
            }
            m /= n;

            a = 0;
            for (i = 0; i < n; i++) {
                a += Math.pow(s[i] - m, 2);
            }

            System.out.println(Math.sqrt(a / n));
        } points = br.readLine().split(" ") points br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " s = new int[n] s new int[n] n m = 0 m 0 for (i = 0; i < n; i++) {
                s[i] = Integer.parseInt(points[i]);
                m += s[i];
            } i = 0; i = 0 i 0 i < n i n i++ i++ i {
                s[i] = Integer.parseInt(points[i]);
                m += s[i];
            } {
                s[i] = Integer.parseInt(points[i]);
                m += s[i];
            } s[i] = Integer.parseInt(points[i]) s[i] s i Integer.parseInt(points[i]) Integer.parseInt Integer points[i] points i m += s[i] m s[i] s i m /= n m n a = 0 a 0 for (i = 0; i < n; i++) {
                a += Math.pow(s[i] - m, 2);
            } i = 0; i = 0 i 0 i < n i n i++ i++ i {
                a += Math.pow(s[i] - m, 2);
            } {
                a += Math.pow(s[i] - m, 2);
            } a += Math.pow(s[i] - m, 2) a Math.pow(s[i] - m, 2) Math.pow Math s[i] - m s[i] s i m 2 System.out.println(Math.sqrt(a / n)) System.out.println System.out System System.out Math.sqrt(a / n) Math.sqrt Math a / n a n String[] args args
import java.io.*;

class Main {
    public static void main (String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n;
        String[] points;
        int[] s;
        int i;
        double m;
        double a;

        while ((n = Integer.parseInt(br.readLine())) != 0) {
            points = br.readLine().split(" ");
            s = new int[n];

            m = 0;
            for (i = 0; i < n; i++) {
                s[i] = Integer.parseInt(points[i]);
                m += s[i];
            }
            m /= n;

            a = 0;
            for (i = 0; i < n; i++) {
                a += Math.pow(s[i] - m, 2);
            }

            System.out.println(Math.sqrt(a / n));
        }

    }
}