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 i;
            int[] ten;
            ten=new int[n];
            int sum=0;
            for(i=0;i<n;i++){
                ten[i]=sc.nextInt();
                sum=sum+ten[i];
            }
            double ave=(double)sum/n;
            double t;
            double s;
            t=0;
            for(i=0;i<n;i++){
                t=t+(ten[i]-ave)*(ten[i]-ave);
            }
            s=t/n;
            System.out.printf("%f\n",Math.sqrt(s));
        }
    }
} 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 i;
            int[] ten;
            ten=new int[n];
            int sum=0;
            for(i=0;i<n;i++){
                ten[i]=sc.nextInt();
                sum=sum+ten[i];
            }
            double ave=(double)sum/n;
            double t;
            double s;
            t=0;
            for(i=0;i<n;i++){
                t=t+(ten[i]-ave)*(ten[i]-ave);
            }
            s=t/n;
            System.out.printf("%f\n",Math.sqrt(s));
        }
    }
} Main public static void main(String args[]){
        Scanner sc=new Scanner(System.in);
        while(true){
            int n= sc.nextInt();
            if(n==0) break;
            int i;
            int[] ten;
            ten=new int[n];
            int sum=0;
            for(i=0;i<n;i++){
                ten[i]=sc.nextInt();
                sum=sum+ten[i];
            }
            double ave=(double)sum/n;
            double t;
            double s;
            t=0;
            for(i=0;i<n;i++){
                t=t+(ten[i]-ave)*(ten[i]-ave);
            }
            s=t/n;
            System.out.printf("%f\n",Math.sqrt(s));
        }
    } main {
        Scanner sc=new Scanner(System.in);
        while(true){
            int n= sc.nextInt();
            if(n==0) break;
            int i;
            int[] ten;
            ten=new int[n];
            int sum=0;
            for(i=0;i<n;i++){
                ten[i]=sc.nextInt();
                sum=sum+ten[i];
            }
            double ave=(double)sum/n;
            double t;
            double s;
            t=0;
            for(i=0;i<n;i++){
                t=t+(ten[i]-ave)*(ten[i]-ave);
            }
            s=t/n;
            System.out.printf("%f\n",Math.sqrt(s));
        }
    } Scanner sc=new Scanner(System.in); sc new Scanner(System.in) while(true){
            int n= sc.nextInt();
            if(n==0) break;
            int i;
            int[] ten;
            ten=new int[n];
            int sum=0;
            for(i=0;i<n;i++){
                ten[i]=sc.nextInt();
                sum=sum+ten[i];
            }
            double ave=(double)sum/n;
            double t;
            double s;
            t=0;
            for(i=0;i<n;i++){
                t=t+(ten[i]-ave)*(ten[i]-ave);
            }
            s=t/n;
            System.out.printf("%f\n",Math.sqrt(s));
        } true {
            int n= sc.nextInt();
            if(n==0) break;
            int i;
            int[] ten;
            ten=new int[n];
            int sum=0;
            for(i=0;i<n;i++){
                ten[i]=sc.nextInt();
                sum=sum+ten[i];
            }
            double ave=(double)sum/n;
            double t;
            double s;
            t=0;
            for(i=0;i<n;i++){
                t=t+(ten[i]-ave)*(ten[i]-ave);
            }
            s=t/n;
            System.out.printf("%f\n",Math.sqrt(s));
        } int n= sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n==0) break; n==0 n 0 break; int i; i int[] ten; ten ten=new int[n] ten new int[n] n int sum=0; sum 0 for(i=0;i<n;i++){
                ten[i]=sc.nextInt();
                sum=sum+ten[i];
            } i=0; i=0 i 0 i<n i n i++ i++ i {
                ten[i]=sc.nextInt();
                sum=sum+ten[i];
            } {
                ten[i]=sc.nextInt();
                sum=sum+ten[i];
            } ten[i]=sc.nextInt() ten[i] ten i sc.nextInt() sc.nextInt sc sum=sum+ten[i] sum sum+ten[i] sum ten[i] ten i double ave=(double)sum/n; ave (double)sum/n (double)sum n double t; t double s; s t=0 t 0 for(i=0;i<n;i++){
                t=t+(ten[i]-ave)*(ten[i]-ave);
            } i=0; i=0 i 0 i<n i n i++ i++ i {
                t=t+(ten[i]-ave)*(ten[i]-ave);
            } {
                t=t+(ten[i]-ave)*(ten[i]-ave);
            } t=t+(ten[i]-ave)*(ten[i]-ave) t t+(ten[i]-ave)*(ten[i]-ave) t (ten[i]-ave)*(ten[i]-ave) (ten[i]-ave) ten[i] ten i ave (ten[i]-ave) ten[i] ten i ave s=t/n s t/n t n System.out.printf("%f\n",Math.sqrt(s)) System.out.printf System.out System System.out "%f\n" Math.sqrt(s) Math.sqrt Math s 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 i;
            int[] ten;
            ten=new int[n];
            int sum=0;
            for(i=0;i<n;i++){
                ten[i]=sc.nextInt();
                sum=sum+ten[i];
            }
            double ave=(double)sum/n;
            double t;
            double s;
            t=0;
            for(i=0;i<n;i++){
                t=t+(ten[i]-ave)*(ten[i]-ave);
            }
            s=t/n;
            System.out.printf("%f\n",Math.sqrt(s));
        }
    }
} 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 i;
            int[] ten;
            ten=new int[n];
            int sum=0;
            for(i=0;i<n;i++){
                ten[i]=sc.nextInt();
                sum=sum+ten[i];
            }
            double ave=(double)sum/n;
            double t;
            double s;
            t=0;
            for(i=0;i<n;i++){
                t=t+(ten[i]-ave)*(ten[i]-ave);
            }
            s=t/n;
            System.out.printf("%f\n",Math.sqrt(s));
        }
    }
} 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 i;
            int[] ten;
            ten=new int[n];
            int sum=0;
            for(i=0;i<n;i++){
                ten[i]=sc.nextInt();
                sum=sum+ten[i];
            }
            double ave=(double)sum/n;
            double t;
            double s;
            t=0;
            for(i=0;i<n;i++){
                t=t+(ten[i]-ave)*(ten[i]-ave);
            }
            s=t/n;
            System.out.printf("%f\n",Math.sqrt(s));
        }
    }
}
