import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        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 sum=0,ave=0,vars=0,var=0;
        for(int i=0;i<n;i++){
            sum = sum+scores[i];
        }
        ave = (double)sum /n;
        for(int i=0;i<n;i++){
            vars = vars+((scores[i]-ave)*(scores[i]-ave));
        }
        var = (double)vars/n;
        System.out.println(Math.sqrt(var));
        }
    }
}
 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 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 sum=0,ave=0,vars=0,var=0;
        for(int i=0;i<n;i++){
            sum = sum+scores[i];
        }
        ave = (double)sum /n;
        for(int i=0;i<n;i++){
            vars = vars+((scores[i]-ave)*(scores[i]-ave));
        }
        var = (double)vars/n;
        System.out.println(Math.sqrt(var));
        }
    }
} Main public static void main(String[] args){
        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 sum=0,ave=0,vars=0,var=0;
        for(int i=0;i<n;i++){
            sum = sum+scores[i];
        }
        ave = (double)sum /n;
        for(int i=0;i<n;i++){
            vars = vars+((scores[i]-ave)*(scores[i]-ave));
        }
        var = (double)vars/n;
        System.out.println(Math.sqrt(var));
        }
    } main {
        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 sum=0,ave=0,vars=0,var=0;
        for(int i=0;i<n;i++){
            sum = sum+scores[i];
        }
        ave = (double)sum /n;
        for(int i=0;i<n;i++){
            vars = vars+((scores[i]-ave)*(scores[i]-ave));
        }
        var = (double)vars/n;
        System.out.println(Math.sqrt(var));
        }
    } Scanner sc = new Scanner(System.in); 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 sum=0,ave=0,vars=0,var=0;
        for(int i=0;i<n;i++){
            sum = sum+scores[i];
        }
        ave = (double)sum /n;
        for(int i=0;i<n;i++){
            vars = vars+((scores[i]-ave)*(scores[i]-ave));
        }
        var = (double)vars/n;
        System.out.println(Math.sqrt(var));
        } 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 sum=0,ave=0,vars=0,var=0;
        for(int i=0;i<n;i++){
            sum = sum+scores[i];
        }
        ave = (double)sum /n;
        for(int i=0;i<n;i++){
            vars = vars+((scores[i]-ave)*(scores[i]-ave));
        }
        var = (double)vars/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 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 sum=0 sum 0 ave=0 ave 0 vars=0 vars 0 var=0; var 0 for(int i=0;i<n;i++){
            sum = sum+scores[i];
        } int i=0; int i=0; i 0 i<n i n i++ i++ i {
            sum = sum+scores[i];
        } {
            sum = sum+scores[i];
        } sum = sum+scores[i] sum sum+scores[i] sum scores[i] scores i ave = (double)sum /n ave (double)sum /n (double)sum n for(int i=0;i<n;i++){
            vars = vars+((scores[i]-ave)*(scores[i]-ave));
        } int i=0; int i=0; i 0 i<n i n i++ i++ i {
            vars = vars+((scores[i]-ave)*(scores[i]-ave));
        } {
            vars = vars+((scores[i]-ave)*(scores[i]-ave));
        } vars = vars+((scores[i]-ave)*(scores[i]-ave)) vars vars+((scores[i]-ave)*(scores[i]-ave)) vars ((scores[i]-ave)*(scores[i]-ave)) (scores[i]-ave) scores[i] scores i ave (scores[i]-ave) scores[i] scores i ave var = (double)vars/n var (double)vars/n (double)vars 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){
        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 sum=0,ave=0,vars=0,var=0;
        for(int i=0;i<n;i++){
            sum = sum+scores[i];
        }
        ave = (double)sum /n;
        for(int i=0;i<n;i++){
            vars = vars+((scores[i]-ave)*(scores[i]-ave));
        }
        var = (double)vars/n;
        System.out.println(Math.sqrt(var));
        }
    }
} public class Main{
    public static void main(String[] args){
        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 sum=0,ave=0,vars=0,var=0;
        for(int i=0;i<n;i++){
            sum = sum+scores[i];
        }
        ave = (double)sum /n;
        for(int i=0;i<n;i++){
            vars = vars+((scores[i]-ave)*(scores[i]-ave));
        }
        var = (double)vars/n;
        System.out.println(Math.sqrt(var));
        }
    }
} Main
import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        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 sum=0,ave=0,vars=0,var=0;
        for(int i=0;i<n;i++){
            sum = sum+scores[i];
        }
        ave = (double)sum /n;
        for(int i=0;i<n;i++){
            vars = vars+((scores[i]-ave)*(scores[i]-ave));
        }
        var = (double)vars/n;
        System.out.println(Math.sqrt(var));
        }
    }
}

