import java.lang.Math;
import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        double m=0;
        double[] si = new double[1001];
        int i,n;
        double z=0;
        while(true){
            n = s.nextInt();
            if(n==0)break;
            for(i=0;i<n;i++){
                si[i]=s.nextInt();
                m+=si[i];
            }
            m/=(double)n;
            for(i=0;i<n;i++)z+=(si[i]-m)*(si[i]-m);
            z/=(double)n;
            System.out.println(Math.sqrt(z));
            m=0;
            z=0;

        }
        
    }
} import java.lang.Math; Math java.lang import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        double m=0;
        double[] si = new double[1001];
        int i,n;
        double z=0;
        while(true){
            n = s.nextInt();
            if(n==0)break;
            for(i=0;i<n;i++){
                si[i]=s.nextInt();
                m+=si[i];
            }
            m/=(double)n;
            for(i=0;i<n;i++)z+=(si[i]-m)*(si[i]-m);
            z/=(double)n;
            System.out.println(Math.sqrt(z));
            m=0;
            z=0;

        }
        
    }
} Main public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        double m=0;
        double[] si = new double[1001];
        int i,n;
        double z=0;
        while(true){
            n = s.nextInt();
            if(n==0)break;
            for(i=0;i<n;i++){
                si[i]=s.nextInt();
                m+=si[i];
            }
            m/=(double)n;
            for(i=0;i<n;i++)z+=(si[i]-m)*(si[i]-m);
            z/=(double)n;
            System.out.println(Math.sqrt(z));
            m=0;
            z=0;

        }
        
    } main {
        Scanner s = new Scanner(System.in);
        double m=0;
        double[] si = new double[1001];
        int i,n;
        double z=0;
        while(true){
            n = s.nextInt();
            if(n==0)break;
            for(i=0;i<n;i++){
                si[i]=s.nextInt();
                m+=si[i];
            }
            m/=(double)n;
            for(i=0;i<n;i++)z+=(si[i]-m)*(si[i]-m);
            z/=(double)n;
            System.out.println(Math.sqrt(z));
            m=0;
            z=0;

        }
        
    } Scanner s = new Scanner(System.in); s new Scanner(System.in) double m=0; m 0 double[] si = new double[1001]; si new double[1001] 1001 int i i n; n double z=0; z 0 while(true){
            n = s.nextInt();
            if(n==0)break;
            for(i=0;i<n;i++){
                si[i]=s.nextInt();
                m+=si[i];
            }
            m/=(double)n;
            for(i=0;i<n;i++)z+=(si[i]-m)*(si[i]-m);
            z/=(double)n;
            System.out.println(Math.sqrt(z));
            m=0;
            z=0;

        } true {
            n = s.nextInt();
            if(n==0)break;
            for(i=0;i<n;i++){
                si[i]=s.nextInt();
                m+=si[i];
            }
            m/=(double)n;
            for(i=0;i<n;i++)z+=(si[i]-m)*(si[i]-m);
            z/=(double)n;
            System.out.println(Math.sqrt(z));
            m=0;
            z=0;

        } n = s.nextInt() n s.nextInt() s.nextInt s if(n==0)break; n==0 n 0 break; for(i=0;i<n;i++){
                si[i]=s.nextInt();
                m+=si[i];
            } i=0; i=0 i 0 i<n i n i++ i++ i {
                si[i]=s.nextInt();
                m+=si[i];
            } {
                si[i]=s.nextInt();
                m+=si[i];
            } si[i]=s.nextInt() si[i] si i s.nextInt() s.nextInt s m+=si[i] m si[i] si i m/=(double)n m (double)n for(i=0;i<n;i++)z+=(si[i]-m)*(si[i]-m); i=0; i=0 i 0 i<n i n i++ i++ i z+=(si[i]-m)*(si[i]-m); z+=(si[i]-m)*(si[i]-m) z (si[i]-m)*(si[i]-m) (si[i]-m) si[i] si i m (si[i]-m) si[i] si i m z/=(double)n z (double)n System.out.println(Math.sqrt(z)) System.out.println System.out System System.out Math.sqrt(z) Math.sqrt Math z m=0 m 0 z=0 z 0 String[] args args public class Main{
    public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        double m=0;
        double[] si = new double[1001];
        int i,n;
        double z=0;
        while(true){
            n = s.nextInt();
            if(n==0)break;
            for(i=0;i<n;i++){
                si[i]=s.nextInt();
                m+=si[i];
            }
            m/=(double)n;
            for(i=0;i<n;i++)z+=(si[i]-m)*(si[i]-m);
            z/=(double)n;
            System.out.println(Math.sqrt(z));
            m=0;
            z=0;

        }
        
    }
} public class Main{
    public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        double m=0;
        double[] si = new double[1001];
        int i,n;
        double z=0;
        while(true){
            n = s.nextInt();
            if(n==0)break;
            for(i=0;i<n;i++){
                si[i]=s.nextInt();
                m+=si[i];
            }
            m/=(double)n;
            for(i=0;i<n;i++)z+=(si[i]-m)*(si[i]-m);
            z/=(double)n;
            System.out.println(Math.sqrt(z));
            m=0;
            z=0;

        }
        
    }
} Main
import java.lang.Math;
import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        double m=0;
        double[] si = new double[1001];
        int i,n;
        double z=0;
        while(true){
            n = s.nextInt();
            if(n==0)break;
            for(i=0;i<n;i++){
                si[i]=s.nextInt();
                m+=si[i];
            }
            m/=(double)n;
            for(i=0;i<n;i++)z+=(si[i]-m)*(si[i]-m);
            z/=(double)n;
            System.out.println(Math.sqrt(z));
            m=0;
            z=0;

        }
        
    }
}
