import java.util.Scanner;

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

        int n = sc.nextInt();

        while (n != 0) {

            int[] score = new int[n];

            double ave = 0.0;
            double val = 0.0;

            for (int i = 0; i < n; i++) {
                score[i] = sc.nextInt();
                ave += score[i];
            }
            ave /= n * 1.0;

            for(int i = 0; i < n; i++)
                val += (score[i] - ave) *  (score[i] - ave);

            val /= n *1.0;

            double sgm = Math.sqrt(val);

            System.out.printf("%f\n", sgm);

            n = sc.nextInt();
        }

        sc.close();
    }
}
 import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();

        while (n != 0) {

            int[] score = new int[n];

            double ave = 0.0;
            double val = 0.0;

            for (int i = 0; i < n; i++) {
                score[i] = sc.nextInt();
                ave += score[i];
            }
            ave /= n * 1.0;

            for(int i = 0; i < n; i++)
                val += (score[i] - ave) *  (score[i] - ave);

            val /= n *1.0;

            double sgm = Math.sqrt(val);

            System.out.printf("%f\n", sgm);

            n = sc.nextInt();
        }

        sc.close();
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();

        while (n != 0) {

            int[] score = new int[n];

            double ave = 0.0;
            double val = 0.0;

            for (int i = 0; i < n; i++) {
                score[i] = sc.nextInt();
                ave += score[i];
            }
            ave /= n * 1.0;

            for(int i = 0; i < n; i++)
                val += (score[i] - ave) *  (score[i] - ave);

            val /= n *1.0;

            double sgm = Math.sqrt(val);

            System.out.printf("%f\n", sgm);

            n = sc.nextInt();
        }

        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();

        while (n != 0) {

            int[] score = new int[n];

            double ave = 0.0;
            double val = 0.0;

            for (int i = 0; i < n; i++) {
                score[i] = sc.nextInt();
                ave += score[i];
            }
            ave /= n * 1.0;

            for(int i = 0; i < n; i++)
                val += (score[i] - ave) *  (score[i] - ave);

            val /= n *1.0;

            double sgm = Math.sqrt(val);

            System.out.printf("%f\n", sgm);

            n = sc.nextInt();
        }

        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc while (n != 0) {

            int[] score = new int[n];

            double ave = 0.0;
            double val = 0.0;

            for (int i = 0; i < n; i++) {
                score[i] = sc.nextInt();
                ave += score[i];
            }
            ave /= n * 1.0;

            for(int i = 0; i < n; i++)
                val += (score[i] - ave) *  (score[i] - ave);

            val /= n *1.0;

            double sgm = Math.sqrt(val);

            System.out.printf("%f\n", sgm);

            n = sc.nextInt();
        } n != 0 n 0 {

            int[] score = new int[n];

            double ave = 0.0;
            double val = 0.0;

            for (int i = 0; i < n; i++) {
                score[i] = sc.nextInt();
                ave += score[i];
            }
            ave /= n * 1.0;

            for(int i = 0; i < n; i++)
                val += (score[i] - ave) *  (score[i] - ave);

            val /= n *1.0;

            double sgm = Math.sqrt(val);

            System.out.printf("%f\n", sgm);

            n = sc.nextInt();
        } int[] score = new int[n]; score new int[n] n double ave = 0.0; ave 0.0 double val = 0.0; val 0.0 for (int i = 0; i < n; i++) {
                score[i] = sc.nextInt();
                ave += score[i];
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                score[i] = sc.nextInt();
                ave += score[i];
            } {
                score[i] = sc.nextInt();
                ave += score[i];
            } score[i] = sc.nextInt() score[i] score i sc.nextInt() sc.nextInt sc ave += score[i] ave score[i] score i ave /= n * 1.0 ave n * 1.0 n 1.0 for(int i = 0; i < n; i++)
                val += (score[i] - ave) *  (score[i] - ave); int i = 0; int i = 0; i 0 i < n i n i++ i++ i val += (score[i] - ave) *  (score[i] - ave); val += (score[i] - ave) *  (score[i] - ave) val (score[i] - ave) *  (score[i] - ave) (score[i] - ave) score[i] score i ave (score[i] - ave) score[i] score i ave val /= n *1.0 val n *1.0 n 1.0 double sgm = Math.sqrt(val); sgm Math.sqrt(val) Math.sqrt Math val System.out.printf("%f\n", sgm) System.out.printf System.out System System.out "%f\n" sgm n = sc.nextInt() n sc.nextInt() sc.nextInt sc sc.close() sc.close sc String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();

        while (n != 0) {

            int[] score = new int[n];

            double ave = 0.0;
            double val = 0.0;

            for (int i = 0; i < n; i++) {
                score[i] = sc.nextInt();
                ave += score[i];
            }
            ave /= n * 1.0;

            for(int i = 0; i < n; i++)
                val += (score[i] - ave) *  (score[i] - ave);

            val /= n *1.0;

            double sgm = Math.sqrt(val);

            System.out.printf("%f\n", sgm);

            n = sc.nextInt();
        }

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

        int n = sc.nextInt();

        while (n != 0) {

            int[] score = new int[n];

            double ave = 0.0;
            double val = 0.0;

            for (int i = 0; i < n; i++) {
                score[i] = sc.nextInt();
                ave += score[i];
            }
            ave /= n * 1.0;

            for(int i = 0; i < n; i++)
                val += (score[i] - ave) *  (score[i] - ave);

            val /= n *1.0;

            double sgm = Math.sqrt(val);

            System.out.printf("%f\n", sgm);

            n = sc.nextInt();
        }

        sc.close();
    }
} Main
import java.util.Scanner;

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

        int n = sc.nextInt();

        while (n != 0) {

            int[] score = new int[n];

            double ave = 0.0;
            double val = 0.0;

            for (int i = 0; i < n; i++) {
                score[i] = sc.nextInt();
                ave += score[i];
            }
            ave /= n * 1.0;

            for(int i = 0; i < n; i++)
                val += (score[i] - ave) *  (score[i] - ave);

            val /= n *1.0;

            double sgm = Math.sqrt(val);

            System.out.printf("%f\n", sgm);

            n = sc.nextInt();
        }

        sc.close();
    }
}

