import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(true){
            int count = sc.nextInt();
            if (count == 0) break;
            int[] score = new int[count];
            int sum = 0;
            double average = 0;
            for (int i=0; i<count; i++) {
                score[i] = sc.nextInt();
                sum += score[i];
            }  
            average = (double)sum/count;
            double d = 0;
            for (int i=0; i<count; i++) {
                d += (score[i]-average)*(score[i]-average);
            }
            double b = (double)d/count;
            System.out.println(Math.sqrt(b));
        }
    }
}
 import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(true){
            int count = sc.nextInt();
            if (count == 0) break;
            int[] score = new int[count];
            int sum = 0;
            double average = 0;
            for (int i=0; i<count; i++) {
                score[i] = sc.nextInt();
                sum += score[i];
            }  
            average = (double)sum/count;
            double d = 0;
            for (int i=0; i<count; i++) {
                d += (score[i]-average)*(score[i]-average);
            }
            double b = (double)d/count;
            System.out.println(Math.sqrt(b));
        }
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(true){
            int count = sc.nextInt();
            if (count == 0) break;
            int[] score = new int[count];
            int sum = 0;
            double average = 0;
            for (int i=0; i<count; i++) {
                score[i] = sc.nextInt();
                sum += score[i];
            }  
            average = (double)sum/count;
            double d = 0;
            for (int i=0; i<count; i++) {
                d += (score[i]-average)*(score[i]-average);
            }
            double b = (double)d/count;
            System.out.println(Math.sqrt(b));
        }
    } main {
        Scanner sc = new Scanner(System.in);
        while(true){
            int count = sc.nextInt();
            if (count == 0) break;
            int[] score = new int[count];
            int sum = 0;
            double average = 0;
            for (int i=0; i<count; i++) {
                score[i] = sc.nextInt();
                sum += score[i];
            }  
            average = (double)sum/count;
            double d = 0;
            for (int i=0; i<count; i++) {
                d += (score[i]-average)*(score[i]-average);
            }
            double b = (double)d/count;
            System.out.println(Math.sqrt(b));
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
            int count = sc.nextInt();
            if (count == 0) break;
            int[] score = new int[count];
            int sum = 0;
            double average = 0;
            for (int i=0; i<count; i++) {
                score[i] = sc.nextInt();
                sum += score[i];
            }  
            average = (double)sum/count;
            double d = 0;
            for (int i=0; i<count; i++) {
                d += (score[i]-average)*(score[i]-average);
            }
            double b = (double)d/count;
            System.out.println(Math.sqrt(b));
        } true {
            int count = sc.nextInt();
            if (count == 0) break;
            int[] score = new int[count];
            int sum = 0;
            double average = 0;
            for (int i=0; i<count; i++) {
                score[i] = sc.nextInt();
                sum += score[i];
            }  
            average = (double)sum/count;
            double d = 0;
            for (int i=0; i<count; i++) {
                d += (score[i]-average)*(score[i]-average);
            }
            double b = (double)d/count;
            System.out.println(Math.sqrt(b));
        } int count = sc.nextInt(); count sc.nextInt() sc.nextInt sc if (count == 0) break; count == 0 count 0 break; int[] score = new int[count]; score new int[count] count int sum = 0; sum 0 double average = 0; average 0 for (int i=0; i<count; i++) {
                score[i] = sc.nextInt();
                sum += score[i];
            } int i=0; int i=0; i 0 i<count i count i++ i++ i {
                score[i] = sc.nextInt();
                sum += score[i];
            } {
                score[i] = sc.nextInt();
                sum += score[i];
            } score[i] = sc.nextInt() score[i] score i sc.nextInt() sc.nextInt sc sum += score[i] sum score[i] score i average = (double)sum/count average (double)sum/count (double)sum count double d = 0; d 0 for (int i=0; i<count; i++) {
                d += (score[i]-average)*(score[i]-average);
            } int i=0; int i=0; i 0 i<count i count i++ i++ i {
                d += (score[i]-average)*(score[i]-average);
            } {
                d += (score[i]-average)*(score[i]-average);
            } d += (score[i]-average)*(score[i]-average) d (score[i]-average)*(score[i]-average) (score[i]-average) score[i] score i average (score[i]-average) score[i] score i average double b = (double)d/count; b (double)d/count (double)d count System.out.println(Math.sqrt(b)) System.out.println System.out System System.out Math.sqrt(b) Math.sqrt Math b String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(true){
            int count = sc.nextInt();
            if (count == 0) break;
            int[] score = new int[count];
            int sum = 0;
            double average = 0;
            for (int i=0; i<count; i++) {
                score[i] = sc.nextInt();
                sum += score[i];
            }  
            average = (double)sum/count;
            double d = 0;
            for (int i=0; i<count; i++) {
                d += (score[i]-average)*(score[i]-average);
            }
            double b = (double)d/count;
            System.out.println(Math.sqrt(b));
        }
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(true){
            int count = sc.nextInt();
            if (count == 0) break;
            int[] score = new int[count];
            int sum = 0;
            double average = 0;
            for (int i=0; i<count; i++) {
                score[i] = sc.nextInt();
                sum += score[i];
            }  
            average = (double)sum/count;
            double d = 0;
            for (int i=0; i<count; i++) {
                d += (score[i]-average)*(score[i]-average);
            }
            double b = (double)d/count;
            System.out.println(Math.sqrt(b));
        }
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(true){
            int count = sc.nextInt();
            if (count == 0) break;
            int[] score = new int[count];
            int sum = 0;
            double average = 0;
            for (int i=0; i<count; i++) {
                score[i] = sc.nextInt();
                sum += score[i];
            }  
            average = (double)sum/count;
            double d = 0;
            for (int i=0; i<count; i++) {
                d += (score[i]-average)*(score[i]-average);
            }
            double b = (double)d/count;
            System.out.println(Math.sqrt(b));
        }
    }
}

