import java.util.Scanner;
public class Main{
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int a = scan.nextInt();
        while (a !=0) {
            double[] b = new double[a];
            for (int x = 0; x < a; x++) {
                b[x] = scan.nextInt();
            }
            double average = 0;
            for (int x = 0; x < a; x++) {
                average = average +b[x];
            }
            average = average / a;
            double var = 0;
            for (int x = 0; x < a; x++) {
                var = var +  ((b[x] - average) *(b[x] - average));
            }
            var = var /a;
            System.out.printf("%.8f\n",Math.sqrt(var));
            a = scan.nextInt();
        }

    }
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int a = scan.nextInt();
        while (a !=0) {
            double[] b = new double[a];
            for (int x = 0; x < a; x++) {
                b[x] = scan.nextInt();
            }
            double average = 0;
            for (int x = 0; x < a; x++) {
                average = average +b[x];
            }
            average = average / a;
            double var = 0;
            for (int x = 0; x < a; x++) {
                var = var +  ((b[x] - average) *(b[x] - average));
            }
            var = var /a;
            System.out.printf("%.8f\n",Math.sqrt(var));
            a = scan.nextInt();
        }

    }
} Main public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int a = scan.nextInt();
        while (a !=0) {
            double[] b = new double[a];
            for (int x = 0; x < a; x++) {
                b[x] = scan.nextInt();
            }
            double average = 0;
            for (int x = 0; x < a; x++) {
                average = average +b[x];
            }
            average = average / a;
            double var = 0;
            for (int x = 0; x < a; x++) {
                var = var +  ((b[x] - average) *(b[x] - average));
            }
            var = var /a;
            System.out.printf("%.8f\n",Math.sqrt(var));
            a = scan.nextInt();
        }

    } main {
        Scanner scan = new Scanner(System.in);
        int a = scan.nextInt();
        while (a !=0) {
            double[] b = new double[a];
            for (int x = 0; x < a; x++) {
                b[x] = scan.nextInt();
            }
            double average = 0;
            for (int x = 0; x < a; x++) {
                average = average +b[x];
            }
            average = average / a;
            double var = 0;
            for (int x = 0; x < a; x++) {
                var = var +  ((b[x] - average) *(b[x] - average));
            }
            var = var /a;
            System.out.printf("%.8f\n",Math.sqrt(var));
            a = scan.nextInt();
        }

    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int a = scan.nextInt(); a scan.nextInt() scan.nextInt scan while (a !=0) {
            double[] b = new double[a];
            for (int x = 0; x < a; x++) {
                b[x] = scan.nextInt();
            }
            double average = 0;
            for (int x = 0; x < a; x++) {
                average = average +b[x];
            }
            average = average / a;
            double var = 0;
            for (int x = 0; x < a; x++) {
                var = var +  ((b[x] - average) *(b[x] - average));
            }
            var = var /a;
            System.out.printf("%.8f\n",Math.sqrt(var));
            a = scan.nextInt();
        } a !=0 a 0 {
            double[] b = new double[a];
            for (int x = 0; x < a; x++) {
                b[x] = scan.nextInt();
            }
            double average = 0;
            for (int x = 0; x < a; x++) {
                average = average +b[x];
            }
            average = average / a;
            double var = 0;
            for (int x = 0; x < a; x++) {
                var = var +  ((b[x] - average) *(b[x] - average));
            }
            var = var /a;
            System.out.printf("%.8f\n",Math.sqrt(var));
            a = scan.nextInt();
        } double[] b = new double[a]; b new double[a] a for (int x = 0; x < a; x++) {
                b[x] = scan.nextInt();
            } int x = 0; int x = 0; x 0 x < a x a x++ x++ x {
                b[x] = scan.nextInt();
            } {
                b[x] = scan.nextInt();
            } b[x] = scan.nextInt() b[x] b x scan.nextInt() scan.nextInt scan double average = 0; average 0 for (int x = 0; x < a; x++) {
                average = average +b[x];
            } int x = 0; int x = 0; x 0 x < a x a x++ x++ x {
                average = average +b[x];
            } {
                average = average +b[x];
            } average = average +b[x] average average +b[x] average b[x] b x average = average / a average average / a average a double var = 0; var 0 for (int x = 0; x < a; x++) {
                var = var +  ((b[x] - average) *(b[x] - average));
            } int x = 0; int x = 0; x 0 x < a x a x++ x++ x {
                var = var +  ((b[x] - average) *(b[x] - average));
            } {
                var = var +  ((b[x] - average) *(b[x] - average));
            } var = var +  ((b[x] - average) *(b[x] - average)) var var +  ((b[x] - average) *(b[x] - average)) var ((b[x] - average) *(b[x] - average)) (b[x] - average) b[x] b x average (b[x] - average) b[x] b x average var = var /a var var /a var a System.out.printf("%.8f\n",Math.sqrt(var)) System.out.printf System.out System System.out "%.8f\n" Math.sqrt(var) Math.sqrt Math var a = scan.nextInt() a scan.nextInt() scan.nextInt scan String[] args args public class Main{
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int a = scan.nextInt();
        while (a !=0) {
            double[] b = new double[a];
            for (int x = 0; x < a; x++) {
                b[x] = scan.nextInt();
            }
            double average = 0;
            for (int x = 0; x < a; x++) {
                average = average +b[x];
            }
            average = average / a;
            double var = 0;
            for (int x = 0; x < a; x++) {
                var = var +  ((b[x] - average) *(b[x] - average));
            }
            var = var /a;
            System.out.printf("%.8f\n",Math.sqrt(var));
            a = scan.nextInt();
        }

    }
} public class Main{
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int a = scan.nextInt();
        while (a !=0) {
            double[] b = new double[a];
            for (int x = 0; x < a; x++) {
                b[x] = scan.nextInt();
            }
            double average = 0;
            for (int x = 0; x < a; x++) {
                average = average +b[x];
            }
            average = average / a;
            double var = 0;
            for (int x = 0; x < a; x++) {
                var = var +  ((b[x] - average) *(b[x] - average));
            }
            var = var /a;
            System.out.printf("%.8f\n",Math.sqrt(var));
            a = scan.nextInt();
        }

    }
} Main
import java.util.Scanner;
public class Main{
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int a = scan.nextInt();
        while (a !=0) {
            double[] b = new double[a];
            for (int x = 0; x < a; x++) {
                b[x] = scan.nextInt();
            }
            double average = 0;
            for (int x = 0; x < a; x++) {
                average = average +b[x];
            }
            average = average / a;
            double var = 0;
            for (int x = 0; x < a; x++) {
                var = var +  ((b[x] - average) *(b[x] - average));
            }
            var = var /a;
            System.out.printf("%.8f\n",Math.sqrt(var));
            a = scan.nextInt();
        }

    }
}
