import java.util.Scanner;

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

        while (true) {
            int amount = scan.nextInt();
            if (amount == 0)
                break;
            int[] scores = new int[amount];
            for (int i = 0; i < amount; i++) {
                scores[i] = scan.nextInt();
            }

            double average = 0.0;
            for (int i = 0; i < amount; i++) {
                average += scores[i];
            }
            average = average / (double)amount;

            double sq_sum = 0.0;
            for (int i = 0; i < amount; i++) {
                sq_sum += Math.pow(scores[i] - average, 2);
            }

            output.append(Math.sqrt(sq_sum / amount)).append('\n');
        }

        System.out.print(output);
    }
} import java.util.Scanner; Scanner java.util class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        StringBuilder output = new StringBuilder();

        while (true) {
            int amount = scan.nextInt();
            if (amount == 0)
                break;
            int[] scores = new int[amount];
            for (int i = 0; i < amount; i++) {
                scores[i] = scan.nextInt();
            }

            double average = 0.0;
            for (int i = 0; i < amount; i++) {
                average += scores[i];
            }
            average = average / (double)amount;

            double sq_sum = 0.0;
            for (int i = 0; i < amount; i++) {
                sq_sum += Math.pow(scores[i] - average, 2);
            }

            output.append(Math.sqrt(sq_sum / amount)).append('\n');
        }

        System.out.print(output);
    }
} Main public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        StringBuilder output = new StringBuilder();

        while (true) {
            int amount = scan.nextInt();
            if (amount == 0)
                break;
            int[] scores = new int[amount];
            for (int i = 0; i < amount; i++) {
                scores[i] = scan.nextInt();
            }

            double average = 0.0;
            for (int i = 0; i < amount; i++) {
                average += scores[i];
            }
            average = average / (double)amount;

            double sq_sum = 0.0;
            for (int i = 0; i < amount; i++) {
                sq_sum += Math.pow(scores[i] - average, 2);
            }

            output.append(Math.sqrt(sq_sum / amount)).append('\n');
        }

        System.out.print(output);
    } main {
        Scanner scan = new Scanner(System.in);
        StringBuilder output = new StringBuilder();

        while (true) {
            int amount = scan.nextInt();
            if (amount == 0)
                break;
            int[] scores = new int[amount];
            for (int i = 0; i < amount; i++) {
                scores[i] = scan.nextInt();
            }

            double average = 0.0;
            for (int i = 0; i < amount; i++) {
                average += scores[i];
            }
            average = average / (double)amount;

            double sq_sum = 0.0;
            for (int i = 0; i < amount; i++) {
                sq_sum += Math.pow(scores[i] - average, 2);
            }

            output.append(Math.sqrt(sq_sum / amount)).append('\n');
        }

        System.out.print(output);
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) StringBuilder output = new StringBuilder(); output new StringBuilder() while (true) {
            int amount = scan.nextInt();
            if (amount == 0)
                break;
            int[] scores = new int[amount];
            for (int i = 0; i < amount; i++) {
                scores[i] = scan.nextInt();
            }

            double average = 0.0;
            for (int i = 0; i < amount; i++) {
                average += scores[i];
            }
            average = average / (double)amount;

            double sq_sum = 0.0;
            for (int i = 0; i < amount; i++) {
                sq_sum += Math.pow(scores[i] - average, 2);
            }

            output.append(Math.sqrt(sq_sum / amount)).append('\n');
        } true {
            int amount = scan.nextInt();
            if (amount == 0)
                break;
            int[] scores = new int[amount];
            for (int i = 0; i < amount; i++) {
                scores[i] = scan.nextInt();
            }

            double average = 0.0;
            for (int i = 0; i < amount; i++) {
                average += scores[i];
            }
            average = average / (double)amount;

            double sq_sum = 0.0;
            for (int i = 0; i < amount; i++) {
                sq_sum += Math.pow(scores[i] - average, 2);
            }

            output.append(Math.sqrt(sq_sum / amount)).append('\n');
        } int amount = scan.nextInt(); amount scan.nextInt() scan.nextInt scan if (amount == 0)
                break; amount == 0 amount 0 break; int[] scores = new int[amount]; scores new int[amount] amount for (int i = 0; i < amount; i++) {
                scores[i] = scan.nextInt();
            } int i = 0; int i = 0; i 0 i < amount i amount i++ i++ i {
                scores[i] = scan.nextInt();
            } {
                scores[i] = scan.nextInt();
            } scores[i] = scan.nextInt() scores[i] scores i scan.nextInt() scan.nextInt scan double average = 0.0; average 0.0 for (int i = 0; i < amount; i++) {
                average += scores[i];
            } int i = 0; int i = 0; i 0 i < amount i amount i++ i++ i {
                average += scores[i];
            } {
                average += scores[i];
            } average += scores[i] average scores[i] scores i average = average / (double)amount average average / (double)amount average (double)amount double sq_sum = 0.0; sq_sum 0.0 for (int i = 0; i < amount; i++) {
                sq_sum += Math.pow(scores[i] - average, 2);
            } int i = 0; int i = 0; i 0 i < amount i amount i++ i++ i {
                sq_sum += Math.pow(scores[i] - average, 2);
            } {
                sq_sum += Math.pow(scores[i] - average, 2);
            } sq_sum += Math.pow(scores[i] - average, 2) sq_sum Math.pow(scores[i] - average, 2) Math.pow Math scores[i] - average scores[i] scores i average 2 output.append(Math.sqrt(sq_sum / amount)).append('\n') output.append(Math.sqrt(sq_sum / amount)).append output.append(Math.sqrt(sq_sum / amount)) output.append output Math.sqrt(sq_sum / amount) Math.sqrt Math sq_sum / amount sq_sum amount '\n' System.out.print(output) System.out.print System.out System System.out output String[] args args
import java.util.Scanner;

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

        while (true) {
            int amount = scan.nextInt();
            if (amount == 0)
                break;
            int[] scores = new int[amount];
            for (int i = 0; i < amount; i++) {
                scores[i] = scan.nextInt();
            }

            double average = 0.0;
            for (int i = 0; i < amount; i++) {
                average += scores[i];
            }
            average = average / (double)amount;

            double sq_sum = 0.0;
            for (int i = 0; i < amount; i++) {
                sq_sum += Math.pow(scores[i] - average, 2);
            }

            output.append(Math.sqrt(sq_sum / amount)).append('\n');
        }

        System.out.print(output);
    }
}