import java.util.*;

public class Main {
    public static void main(String[] args) {
        try(Scanner scn = new Scanner(System.in)) {
            int n;
            while((n = scn.nextInt()) > 0) {
                double sum = 0, sd = 0;
                double[] s = new double[n];

                for(int i = 0; i < n; i++) {
                    s[i] = scn.nextDouble();
                    sum += s[i];
                }
                double avg = sum / n;
                for(int i = 0; i < n; i++) {
                    sd += Math.pow((s[i] - avg), 2);
                }
                System.out.println(Math.sqrt(sd / n));
            }
        }
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        try(Scanner scn = new Scanner(System.in)) {
            int n;
            while((n = scn.nextInt()) > 0) {
                double sum = 0, sd = 0;
                double[] s = new double[n];

                for(int i = 0; i < n; i++) {
                    s[i] = scn.nextDouble();
                    sum += s[i];
                }
                double avg = sum / n;
                for(int i = 0; i < n; i++) {
                    sd += Math.pow((s[i] - avg), 2);
                }
                System.out.println(Math.sqrt(sd / n));
            }
        }
    }
} Main public static void main(String[] args) {
        try(Scanner scn = new Scanner(System.in)) {
            int n;
            while((n = scn.nextInt()) > 0) {
                double sum = 0, sd = 0;
                double[] s = new double[n];

                for(int i = 0; i < n; i++) {
                    s[i] = scn.nextDouble();
                    sum += s[i];
                }
                double avg = sum / n;
                for(int i = 0; i < n; i++) {
                    sd += Math.pow((s[i] - avg), 2);
                }
                System.out.println(Math.sqrt(sd / n));
            }
        }
    } main {
        try(Scanner scn = new Scanner(System.in)) {
            int n;
            while((n = scn.nextInt()) > 0) {
                double sum = 0, sd = 0;
                double[] s = new double[n];

                for(int i = 0; i < n; i++) {
                    s[i] = scn.nextDouble();
                    sum += s[i];
                }
                double avg = sum / n;
                for(int i = 0; i < n; i++) {
                    sd += Math.pow((s[i] - avg), 2);
                }
                System.out.println(Math.sqrt(sd / n));
            }
        }
    } try(Scanner scn = new Scanner(System.in)) {
            int n;
            while((n = scn.nextInt()) > 0) {
                double sum = 0, sd = 0;
                double[] s = new double[n];

                for(int i = 0; i < n; i++) {
                    s[i] = scn.nextDouble();
                    sum += s[i];
                }
                double avg = sum / n;
                for(int i = 0; i < n; i++) {
                    sd += Math.pow((s[i] - avg), 2);
                }
                System.out.println(Math.sqrt(sd / n));
            }
        } {
            int n;
            while((n = scn.nextInt()) > 0) {
                double sum = 0, sd = 0;
                double[] s = new double[n];

                for(int i = 0; i < n; i++) {
                    s[i] = scn.nextDouble();
                    sum += s[i];
                }
                double avg = sum / n;
                for(int i = 0; i < n; i++) {
                    sd += Math.pow((s[i] - avg), 2);
                }
                System.out.println(Math.sqrt(sd / n));
            }
        } Scanner scn = new Scanner(System.in) Scanner scn = new Scanner(System.in) new Scanner(System.in) int n; n while((n = scn.nextInt()) > 0) {
                double sum = 0, sd = 0;
                double[] s = new double[n];

                for(int i = 0; i < n; i++) {
                    s[i] = scn.nextDouble();
                    sum += s[i];
                }
                double avg = sum / n;
                for(int i = 0; i < n; i++) {
                    sd += Math.pow((s[i] - avg), 2);
                }
                System.out.println(Math.sqrt(sd / n));
            } (n = scn.nextInt()) > 0 (n = scn.nextInt()) n scn.nextInt() scn.nextInt scn 0 {
                double sum = 0, sd = 0;
                double[] s = new double[n];

                for(int i = 0; i < n; i++) {
                    s[i] = scn.nextDouble();
                    sum += s[i];
                }
                double avg = sum / n;
                for(int i = 0; i < n; i++) {
                    sd += Math.pow((s[i] - avg), 2);
                }
                System.out.println(Math.sqrt(sd / n));
            } double sum = 0 sum 0 sd = 0; sd 0 double[] s = new double[n]; s new double[n] n for(int i = 0; i < n; i++) {
                    s[i] = scn.nextDouble();
                    sum += s[i];
                } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                    s[i] = scn.nextDouble();
                    sum += s[i];
                } {
                    s[i] = scn.nextDouble();
                    sum += s[i];
                } s[i] = scn.nextDouble() s[i] s i scn.nextDouble() scn.nextDouble scn sum += s[i] sum s[i] s i double avg = sum / n; avg sum / n sum n for(int i = 0; i < n; i++) {
                    sd += Math.pow((s[i] - avg), 2);
                } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                    sd += Math.pow((s[i] - avg), 2);
                } {
                    sd += Math.pow((s[i] - avg), 2);
                } sd += Math.pow((s[i] - avg), 2) sd Math.pow((s[i] - avg), 2) Math.pow Math (s[i] - avg) s[i] s i avg 2 System.out.println(Math.sqrt(sd / n)) System.out.println System.out System System.out Math.sqrt(sd / n) Math.sqrt Math sd / n sd n String[] args args public class Main {
    public static void main(String[] args) {
        try(Scanner scn = new Scanner(System.in)) {
            int n;
            while((n = scn.nextInt()) > 0) {
                double sum = 0, sd = 0;
                double[] s = new double[n];

                for(int i = 0; i < n; i++) {
                    s[i] = scn.nextDouble();
                    sum += s[i];
                }
                double avg = sum / n;
                for(int i = 0; i < n; i++) {
                    sd += Math.pow((s[i] - avg), 2);
                }
                System.out.println(Math.sqrt(sd / n));
            }
        }
    }
} public class Main {
    public static void main(String[] args) {
        try(Scanner scn = new Scanner(System.in)) {
            int n;
            while((n = scn.nextInt()) > 0) {
                double sum = 0, sd = 0;
                double[] s = new double[n];

                for(int i = 0; i < n; i++) {
                    s[i] = scn.nextDouble();
                    sum += s[i];
                }
                double avg = sum / n;
                for(int i = 0; i < n; i++) {
                    sd += Math.pow((s[i] - avg), 2);
                }
                System.out.println(Math.sqrt(sd / n));
            }
        }
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) {
        try(Scanner scn = new Scanner(System.in)) {
            int n;
            while((n = scn.nextInt()) > 0) {
                double sum = 0, sd = 0;
                double[] s = new double[n];

                for(int i = 0; i < n; i++) {
                    s[i] = scn.nextDouble();
                    sum += s[i];
                }
                double avg = sum / n;
                for(int i = 0; i < n; i++) {
                    sd += Math.pow((s[i] - avg), 2);
                }
                System.out.println(Math.sqrt(sd / n));
            }
        }
    }
}