import java.util.Scanner;

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

public class Main{
    public static void main (String[] args){
        try(Scanner sc = new Scanner(System.in)){
            while(true){
                int n = sc.nextInt();
                if(n == 0){break;}
                int[] scores = new int[n];
                for(int i = 0;i < scores.length;i++){
                    scores[i] = sc.nextInt();
                }
                double average = 0,deviation = 0,variance = 0;
                int sum = 0;
                for(int i = 0;i < scores.length;i++){
                    sum = sum + scores[i];
                }
                average = (double)sum / scores.length;
                for(int i = 0;i < scores.length;i++){
                    deviation = deviation + (scores[i] - average)*(scores[i] - average);
                }
                variance = deviation / scores.length;
                System.out.println(Math.sqrt(variance));
            }
        }
    }
}
