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];
                int sum=0;
                double sum2=0;
                for(int i=0;i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                double ave= (double)sum/n,var = 0;
                double[]scores2 = new double[n];
                for(int i=0;i<scores.length;i++){
                    scores2[i] = (scores[i] - ave)*(scores[i] - ave);
                    sum2 += scores2[i];
                }
                var = sum2 /n;
                System.out.println(Math.sqrt(var));
            }
        }
    }
} 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];
                int sum=0;
                double sum2=0;
                for(int i=0;i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                double ave= (double)sum/n,var = 0;
                double[]scores2 = new double[n];
                for(int i=0;i<scores.length;i++){
                    scores2[i] = (scores[i] - ave)*(scores[i] - ave);
                    sum2 += scores2[i];
                }
                var = sum2 /n;
                System.out.println(Math.sqrt(var));
            }
        }
    }
} 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];
                int sum=0;
                double sum2=0;
                for(int i=0;i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                double ave= (double)sum/n,var = 0;
                double[]scores2 = new double[n];
                for(int i=0;i<scores.length;i++){
                    scores2[i] = (scores[i] - ave)*(scores[i] - ave);
                    sum2 += scores2[i];
                }
                var = sum2 /n;
                System.out.println(Math.sqrt(var));
            }
        }
    } main {
        try(Scanner sc = new Scanner(System.in);){
            while(true){
                int n = sc.nextInt();
                if(n== 0)break;
                int[]scores = new int[n];
                int sum=0;
                double sum2=0;
                for(int i=0;i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                double ave= (double)sum/n,var = 0;
                double[]scores2 = new double[n];
                for(int i=0;i<scores.length;i++){
                    scores2[i] = (scores[i] - ave)*(scores[i] - ave);
                    sum2 += scores2[i];
                }
                var = sum2 /n;
                System.out.println(Math.sqrt(var));
            }
        }
    } try(Scanner sc = new Scanner(System.in);){
            while(true){
                int n = sc.nextInt();
                if(n== 0)break;
                int[]scores = new int[n];
                int sum=0;
                double sum2=0;
                for(int i=0;i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                double ave= (double)sum/n,var = 0;
                double[]scores2 = new double[n];
                for(int i=0;i<scores.length;i++){
                    scores2[i] = (scores[i] - ave)*(scores[i] - ave);
                    sum2 += scores2[i];
                }
                var = sum2 /n;
                System.out.println(Math.sqrt(var));
            }
        } {
            while(true){
                int n = sc.nextInt();
                if(n== 0)break;
                int[]scores = new int[n];
                int sum=0;
                double sum2=0;
                for(int i=0;i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                double ave= (double)sum/n,var = 0;
                double[]scores2 = new double[n];
                for(int i=0;i<scores.length;i++){
                    scores2[i] = (scores[i] - ave)*(scores[i] - ave);
                    sum2 += scores2[i];
                }
                var = sum2 /n;
                System.out.println(Math.sqrt(var));
            }
        } 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];
                int sum=0;
                double sum2=0;
                for(int i=0;i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                double ave= (double)sum/n,var = 0;
                double[]scores2 = new double[n];
                for(int i=0;i<scores.length;i++){
                    scores2[i] = (scores[i] - ave)*(scores[i] - ave);
                    sum2 += scores2[i];
                }
                var = sum2 /n;
                System.out.println(Math.sqrt(var));
            } true {
                int n = sc.nextInt();
                if(n== 0)break;
                int[]scores = new int[n];
                int sum=0;
                double sum2=0;
                for(int i=0;i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                double ave= (double)sum/n,var = 0;
                double[]scores2 = new double[n];
                for(int i=0;i<scores.length;i++){
                    scores2[i] = (scores[i] - ave)*(scores[i] - ave);
                    sum2 += scores2[i];
                }
                var = sum2 /n;
                System.out.println(Math.sqrt(var));
            } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n== 0)break; n== 0 n 0 break; int[]scores = new int[n]; scores new int[n] n int sum=0; sum 0 double sum2=0; sum2 0 for(int i=0;i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                } int i=0; int i=0; i 0 i<scores.length i scores.length scores scores.length i++ i++ i {
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                } {
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                } scores[i] = sc.nextInt() scores[i] scores i sc.nextInt() sc.nextInt sc sum += scores[i] sum scores[i] scores i double ave= (double)sum/n ave (double)sum/n (double)sum n var = 0; var 0 double[]scores2 = new double[n]; scores2 new double[n] n for(int i=0;i<scores.length;i++){
                    scores2[i] = (scores[i] - ave)*(scores[i] - ave);
                    sum2 += scores2[i];
                } int i=0; int i=0; i 0 i<scores.length i scores.length scores scores.length i++ i++ i {
                    scores2[i] = (scores[i] - ave)*(scores[i] - ave);
                    sum2 += scores2[i];
                } {
                    scores2[i] = (scores[i] - ave)*(scores[i] - ave);
                    sum2 += scores2[i];
                } scores2[i] = (scores[i] - ave)*(scores[i] - ave) scores2[i] scores2 i (scores[i] - ave)*(scores[i] - ave) (scores[i] - ave) scores[i] scores i ave (scores[i] - ave) scores[i] scores i ave sum2 += scores2[i] sum2 scores2[i] scores2 i var = sum2 /n var sum2 /n sum2 n System.out.println(Math.sqrt(var)) System.out.println System.out System System.out Math.sqrt(var) Math.sqrt Math var 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];
                int sum=0;
                double sum2=0;
                for(int i=0;i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                double ave= (double)sum/n,var = 0;
                double[]scores2 = new double[n];
                for(int i=0;i<scores.length;i++){
                    scores2[i] = (scores[i] - ave)*(scores[i] - ave);
                    sum2 += scores2[i];
                }
                var = sum2 /n;
                System.out.println(Math.sqrt(var));
            }
        }
    }
} 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];
                int sum=0;
                double sum2=0;
                for(int i=0;i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                double ave= (double)sum/n,var = 0;
                double[]scores2 = new double[n];
                for(int i=0;i<scores.length;i++){
                    scores2[i] = (scores[i] - ave)*(scores[i] - ave);
                    sum2 += scores2[i];
                }
                var = sum2 /n;
                System.out.println(Math.sqrt(var));
            }
        }
    }
} 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];
                int sum=0;
                double sum2=0;
                for(int i=0;i<scores.length;i++){
                    scores[i] = sc.nextInt();
                    sum += scores[i];
                }
                double ave= (double)sum/n,var = 0;
                double[]scores2 = new double[n];
                for(int i=0;i<scores.length;i++){
                    scores2[i] = (scores[i] - ave)*(scores[i] - ave);
                    sum2 += scores2[i];
                }
                var = sum2 /n;
                System.out.println(Math.sqrt(var));
            }
        }
    }
}
