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[] s;
            s = new int[n];
            int sum=0;
            double ave, bunsan=0.0;
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum+= s[i];
            }
            ave = (double)sum/n;
            for(int j=0;j<n;j++){
                bunsan += (double)(s[j]-ave) * (s[j]-ave) / n;
            }
            System.out.println(Math.sqrt(bunsan));
        }
        sc.close();
    }
} 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[] s;
            s = new int[n];
            int sum=0;
            double ave, bunsan=0.0;
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum+= s[i];
            }
            ave = (double)sum/n;
            for(int j=0;j<n;j++){
                bunsan += (double)(s[j]-ave) * (s[j]-ave) / n;
            }
            System.out.println(Math.sqrt(bunsan));
        }
        sc.close();
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n==0) break;
            int[] s;
            s = new int[n];
            int sum=0;
            double ave, bunsan=0.0;
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum+= s[i];
            }
            ave = (double)sum/n;
            for(int j=0;j<n;j++){
                bunsan += (double)(s[j]-ave) * (s[j]-ave) / n;
            }
            System.out.println(Math.sqrt(bunsan));
        }
        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
        while(true){
            int n = sc.nextInt();
            if(n==0) break;
            int[] s;
            s = new int[n];
            int sum=0;
            double ave, bunsan=0.0;
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum+= s[i];
            }
            ave = (double)sum/n;
            for(int j=0;j<n;j++){
                bunsan += (double)(s[j]-ave) * (s[j]-ave) / n;
            }
            System.out.println(Math.sqrt(bunsan));
        }
        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
            int n = sc.nextInt();
            if(n==0) break;
            int[] s;
            s = new int[n];
            int sum=0;
            double ave, bunsan=0.0;
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum+= s[i];
            }
            ave = (double)sum/n;
            for(int j=0;j<n;j++){
                bunsan += (double)(s[j]-ave) * (s[j]-ave) / n;
            }
            System.out.println(Math.sqrt(bunsan));
        } true {
            int n = sc.nextInt();
            if(n==0) break;
            int[] s;
            s = new int[n];
            int sum=0;
            double ave, bunsan=0.0;
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum+= s[i];
            }
            ave = (double)sum/n;
            for(int j=0;j<n;j++){
                bunsan += (double)(s[j]-ave) * (s[j]-ave) / n;
            }
            System.out.println(Math.sqrt(bunsan));
        } int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n==0) break; n==0 n 0 break; int[] s; s s = new int[n] s new int[n] n int sum=0; sum 0 double ave ave bunsan=0.0; bunsan 0.0 for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum+= s[i];
            } int i=0; int i=0; i 0 i<n i n i++ i++ i {
                s[i] = sc.nextInt();
                sum+= s[i];
            } {
                s[i] = sc.nextInt();
                sum+= s[i];
            } s[i] = sc.nextInt() s[i] s i sc.nextInt() sc.nextInt sc sum+= s[i] sum s[i] s i ave = (double)sum/n ave (double)sum/n (double)sum n for(int j=0;j<n;j++){
                bunsan += (double)(s[j]-ave) * (s[j]-ave) / n;
            } int j=0; int j=0; j 0 j<n j n j++ j++ j {
                bunsan += (double)(s[j]-ave) * (s[j]-ave) / n;
            } {
                bunsan += (double)(s[j]-ave) * (s[j]-ave) / n;
            } bunsan += (double)(s[j]-ave) * (s[j]-ave) / n bunsan (double)(s[j]-ave) * (s[j]-ave) / n (double)(s[j]-ave) * (s[j]-ave) (double)(s[j]-ave) s[j] s j ave (s[j]-ave) s[j] s j ave n System.out.println(Math.sqrt(bunsan)) System.out.println System.out System System.out Math.sqrt(bunsan) Math.sqrt Math bunsan sc.close() sc.close sc 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[] s;
            s = new int[n];
            int sum=0;
            double ave, bunsan=0.0;
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum+= s[i];
            }
            ave = (double)sum/n;
            for(int j=0;j<n;j++){
                bunsan += (double)(s[j]-ave) * (s[j]-ave) / n;
            }
            System.out.println(Math.sqrt(bunsan));
        }
        sc.close();
    }
} 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[] s;
            s = new int[n];
            int sum=0;
            double ave, bunsan=0.0;
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum+= s[i];
            }
            ave = (double)sum/n;
            for(int j=0;j<n;j++){
                bunsan += (double)(s[j]-ave) * (s[j]-ave) / n;
            }
            System.out.println(Math.sqrt(bunsan));
        }
        sc.close();
    }
} 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[] s;
            s = new int[n];
            int sum=0;
            double ave, bunsan=0.0;
            for(int i=0;i<n;i++){
                s[i] = sc.nextInt();
                sum+= s[i];
            }
            ave = (double)sum/n;
            for(int j=0;j<n;j++){
                bunsan += (double)(s[j]-ave) * (s[j]-ave) / n;
            }
            System.out.println(Math.sqrt(bunsan));
        }
        sc.close();
    }
}
