import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double ave;
        double s;
        while(true) {
            double sum=0;
            double tmp=0;
            int num = sc.nextInt();
            if (num == 0) break;
            int[] score = new int[num];
            for (int i = 0; i < num; i++) {
                score[i] = sc.nextInt();
                sum += (double)score[i];
            }
            ave = sum / (double) num;
            for (int i = 0; i < num; i++) {
                tmp += Math.pow((double) score[i] - ave, 2.0);
            }
            s = Math.sqrt(tmp / num);
            System.out.printf("%.8f\n", s);
        }
    }
}
 import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double ave;
        double s;
        while(true) {
            double sum=0;
            double tmp=0;
            int num = sc.nextInt();
            if (num == 0) break;
            int[] score = new int[num];
            for (int i = 0; i < num; i++) {
                score[i] = sc.nextInt();
                sum += (double)score[i];
            }
            ave = sum / (double) num;
            for (int i = 0; i < num; i++) {
                tmp += Math.pow((double) score[i] - ave, 2.0);
            }
            s = Math.sqrt(tmp / num);
            System.out.printf("%.8f\n", s);
        }
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double ave;
        double s;
        while(true) {
            double sum=0;
            double tmp=0;
            int num = sc.nextInt();
            if (num == 0) break;
            int[] score = new int[num];
            for (int i = 0; i < num; i++) {
                score[i] = sc.nextInt();
                sum += (double)score[i];
            }
            ave = sum / (double) num;
            for (int i = 0; i < num; i++) {
                tmp += Math.pow((double) score[i] - ave, 2.0);
            }
            s = Math.sqrt(tmp / num);
            System.out.printf("%.8f\n", s);
        }
    } main {
        Scanner sc = new Scanner(System.in);
        double ave;
        double s;
        while(true) {
            double sum=0;
            double tmp=0;
            int num = sc.nextInt();
            if (num == 0) break;
            int[] score = new int[num];
            for (int i = 0; i < num; i++) {
                score[i] = sc.nextInt();
                sum += (double)score[i];
            }
            ave = sum / (double) num;
            for (int i = 0; i < num; i++) {
                tmp += Math.pow((double) score[i] - ave, 2.0);
            }
            s = Math.sqrt(tmp / num);
            System.out.printf("%.8f\n", s);
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double ave; ave double s; s while(true) {
            double sum=0;
            double tmp=0;
            int num = sc.nextInt();
            if (num == 0) break;
            int[] score = new int[num];
            for (int i = 0; i < num; i++) {
                score[i] = sc.nextInt();
                sum += (double)score[i];
            }
            ave = sum / (double) num;
            for (int i = 0; i < num; i++) {
                tmp += Math.pow((double) score[i] - ave, 2.0);
            }
            s = Math.sqrt(tmp / num);
            System.out.printf("%.8f\n", s);
        } true {
            double sum=0;
            double tmp=0;
            int num = sc.nextInt();
            if (num == 0) break;
            int[] score = new int[num];
            for (int i = 0; i < num; i++) {
                score[i] = sc.nextInt();
                sum += (double)score[i];
            }
            ave = sum / (double) num;
            for (int i = 0; i < num; i++) {
                tmp += Math.pow((double) score[i] - ave, 2.0);
            }
            s = Math.sqrt(tmp / num);
            System.out.printf("%.8f\n", s);
        } double sum=0; sum 0 double tmp=0; tmp 0 int num = sc.nextInt(); num sc.nextInt() sc.nextInt sc if (num == 0) break; num == 0 num 0 break; int[] score = new int[num]; score new int[num] num for (int i = 0; i < num; i++) {
                score[i] = sc.nextInt();
                sum += (double)score[i];
            } int i = 0; int i = 0; i 0 i < num i num i++ i++ i {
                score[i] = sc.nextInt();
                sum += (double)score[i];
            } {
                score[i] = sc.nextInt();
                sum += (double)score[i];
            } score[i] = sc.nextInt() score[i] score i sc.nextInt() sc.nextInt sc sum += (double)score[i] sum (double)score[i] score i ave = sum / (double) num ave sum / (double) num sum (double) num for (int i = 0; i < num; i++) {
                tmp += Math.pow((double) score[i] - ave, 2.0);
            } int i = 0; int i = 0; i 0 i < num i num i++ i++ i {
                tmp += Math.pow((double) score[i] - ave, 2.0);
            } {
                tmp += Math.pow((double) score[i] - ave, 2.0);
            } tmp += Math.pow((double) score[i] - ave, 2.0) tmp Math.pow((double) score[i] - ave, 2.0) Math.pow Math (double) score[i] - ave (double) score[i] score i ave 2.0 s = Math.sqrt(tmp / num) s Math.sqrt(tmp / num) Math.sqrt Math tmp / num tmp num System.out.printf("%.8f\n", s) System.out.printf System.out System System.out "%.8f\n" s String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double ave;
        double s;
        while(true) {
            double sum=0;
            double tmp=0;
            int num = sc.nextInt();
            if (num == 0) break;
            int[] score = new int[num];
            for (int i = 0; i < num; i++) {
                score[i] = sc.nextInt();
                sum += (double)score[i];
            }
            ave = sum / (double) num;
            for (int i = 0; i < num; i++) {
                tmp += Math.pow((double) score[i] - ave, 2.0);
            }
            s = Math.sqrt(tmp / num);
            System.out.printf("%.8f\n", s);
        }
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double ave;
        double s;
        while(true) {
            double sum=0;
            double tmp=0;
            int num = sc.nextInt();
            if (num == 0) break;
            int[] score = new int[num];
            for (int i = 0; i < num; i++) {
                score[i] = sc.nextInt();
                sum += (double)score[i];
            }
            ave = sum / (double) num;
            for (int i = 0; i < num; i++) {
                tmp += Math.pow((double) score[i] - ave, 2.0);
            }
            s = Math.sqrt(tmp / num);
            System.out.printf("%.8f\n", s);
        }
    }
} Main
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double ave;
        double s;
        while(true) {
            double sum=0;
            double tmp=0;
            int num = sc.nextInt();
            if (num == 0) break;
            int[] score = new int[num];
            for (int i = 0; i < num; i++) {
                score[i] = sc.nextInt();
                sum += (double)score[i];
            }
            ave = sum / (double) num;
            for (int i = 0; i < num; i++) {
                tmp += Math.pow((double) score[i] - ave, 2.0);
            }
            s = Math.sqrt(tmp / num);
            System.out.printf("%.8f\n", s);
        }
    }
}

