import java.util.Random;
import java.util.Scanner;

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

        int n;
        while (true) {
            n = scanner.nextInt();
            if (n == 0) break;

            int sum = 0, sum2 = 0;
            for (int i = 0; i < n; ++i) {
                int a = scanner.nextInt();
                sum += a;
                sum2 += a * a;
            }

            System.out.println(Math.sqrt(sum2 / (double)n - Math.pow((sum / (double)n), 2)));
        }
    }
}
 import java.util.Random; Random java.util import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int n;
        while (true) {
            n = scanner.nextInt();
            if (n == 0) break;

            int sum = 0, sum2 = 0;
            for (int i = 0; i < n; ++i) {
                int a = scanner.nextInt();
                sum += a;
                sum2 += a * a;
            }

            System.out.println(Math.sqrt(sum2 / (double)n - Math.pow((sum / (double)n), 2)));
        }
    }
} Main public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int n;
        while (true) {
            n = scanner.nextInt();
            if (n == 0) break;

            int sum = 0, sum2 = 0;
            for (int i = 0; i < n; ++i) {
                int a = scanner.nextInt();
                sum += a;
                sum2 += a * a;
            }

            System.out.println(Math.sqrt(sum2 / (double)n - Math.pow((sum / (double)n), 2)));
        }
    } main {
        Scanner scanner = new Scanner(System.in);

        int n;
        while (true) {
            n = scanner.nextInt();
            if (n == 0) break;

            int sum = 0, sum2 = 0;
            for (int i = 0; i < n; ++i) {
                int a = scanner.nextInt();
                sum += a;
                sum2 += a * a;
            }

            System.out.println(Math.sqrt(sum2 / (double)n - Math.pow((sum / (double)n), 2)));
        }
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int n; n while (true) {
            n = scanner.nextInt();
            if (n == 0) break;

            int sum = 0, sum2 = 0;
            for (int i = 0; i < n; ++i) {
                int a = scanner.nextInt();
                sum += a;
                sum2 += a * a;
            }

            System.out.println(Math.sqrt(sum2 / (double)n - Math.pow((sum / (double)n), 2)));
        } true {
            n = scanner.nextInt();
            if (n == 0) break;

            int sum = 0, sum2 = 0;
            for (int i = 0; i < n; ++i) {
                int a = scanner.nextInt();
                sum += a;
                sum2 += a * a;
            }

            System.out.println(Math.sqrt(sum2 / (double)n - Math.pow((sum / (double)n), 2)));
        } n = scanner.nextInt() n scanner.nextInt() scanner.nextInt scanner if (n == 0) break; n == 0 n 0 break; int sum = 0 sum 0 sum2 = 0; sum2 0 for (int i = 0; i < n; ++i) {
                int a = scanner.nextInt();
                sum += a;
                sum2 += a * a;
            } int i = 0; int i = 0; i 0 i < n i n ++i ++i i {
                int a = scanner.nextInt();
                sum += a;
                sum2 += a * a;
            } {
                int a = scanner.nextInt();
                sum += a;
                sum2 += a * a;
            } int a = scanner.nextInt(); a scanner.nextInt() scanner.nextInt scanner sum += a sum a sum2 += a * a sum2 a * a a a System.out.println(Math.sqrt(sum2 / (double)n - Math.pow((sum / (double)n), 2))) System.out.println System.out System System.out Math.sqrt(sum2 / (double)n - Math.pow((sum / (double)n), 2)) Math.sqrt Math sum2 / (double)n - Math.pow((sum / (double)n), 2) sum2 / (double)n sum2 (double)n Math.pow((sum / (double)n), 2) Math.pow Math (sum / (double)n) sum (double)n 2 String[] args args public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int n;
        while (true) {
            n = scanner.nextInt();
            if (n == 0) break;

            int sum = 0, sum2 = 0;
            for (int i = 0; i < n; ++i) {
                int a = scanner.nextInt();
                sum += a;
                sum2 += a * a;
            }

            System.out.println(Math.sqrt(sum2 / (double)n - Math.pow((sum / (double)n), 2)));
        }
    }
} public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int n;
        while (true) {
            n = scanner.nextInt();
            if (n == 0) break;

            int sum = 0, sum2 = 0;
            for (int i = 0; i < n; ++i) {
                int a = scanner.nextInt();
                sum += a;
                sum2 += a * a;
            }

            System.out.println(Math.sqrt(sum2 / (double)n - Math.pow((sum / (double)n), 2)));
        }
    }
} Main
import java.util.Random;
import java.util.Scanner;

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

        int n;
        while (true) {
            n = scanner.nextInt();
            if (n == 0) break;

            int sum = 0, sum2 = 0;
            for (int i = 0; i < n; ++i) {
                int a = scanner.nextInt();
                sum += a;
                sum2 += a * a;
            }

            System.out.println(Math.sqrt(sum2 / (double)n - Math.pow((sum / (double)n), 2)));
        }
    }
}

