import java.awt.print.Printable;
import java.util.Scanner;
import javax.sound.midi.SysexMessage;
import java.lang.Math;
  
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];
        int sum=0;
        double ave=0.0;
        double div=0.0;
        for(int i=0;i<n;i++){
            scores[i]=sc.nextInt();
            sum+=scores[i];
        }
        ave = (double)sum/(double)n;

        for(int i=0;i<n;i++){
            div += (Math.pow(scores[i]-ave,2))/n;
        }

        System.out.println(Math.pow(div, 0.5));
     }
        sc.close();
        
    }   
} import java.awt.print.Printable; Printable java.awt.print import java.util.Scanner; Scanner java.util import javax.sound.midi.SysexMessage; SysexMessage javax.sound.midi import java.lang.Math; Math java.lang 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];
        int sum=0;
        double ave=0.0;
        double div=0.0;
        for(int i=0;i<n;i++){
            scores[i]=sc.nextInt();
            sum+=scores[i];
        }
        ave = (double)sum/(double)n;

        for(int i=0;i<n;i++){
            div += (Math.pow(scores[i]-ave,2))/n;
        }

        System.out.println(Math.pow(div, 0.5));
     }
        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 scores[]=new int[n];
        int sum=0;
        double ave=0.0;
        double div=0.0;
        for(int i=0;i<n;i++){
            scores[i]=sc.nextInt();
            sum+=scores[i];
        }
        ave = (double)sum/(double)n;

        for(int i=0;i<n;i++){
            div += (Math.pow(scores[i]-ave,2))/n;
        }

        System.out.println(Math.pow(div, 0.5));
     }
        sc.close();
        
    } main {

        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 ave=0.0;
        double div=0.0;
        for(int i=0;i<n;i++){
            scores[i]=sc.nextInt();
            sum+=scores[i];
        }
        ave = (double)sum/(double)n;

        for(int i=0;i<n;i++){
            div += (Math.pow(scores[i]-ave,2))/n;
        }

        System.out.println(Math.pow(div, 0.5));
     }
        sc.close();
        
    } 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];
        int sum=0;
        double ave=0.0;
        double div=0.0;
        for(int i=0;i<n;i++){
            scores[i]=sc.nextInt();
            sum+=scores[i];
        }
        ave = (double)sum/(double)n;

        for(int i=0;i<n;i++){
            div += (Math.pow(scores[i]-ave,2))/n;
        }

        System.out.println(Math.pow(div, 0.5));
     } true {
        int n = sc.nextInt();
        if(n==0)
            break;
        int scores[]=new int[n];
        int sum=0;
        double ave=0.0;
        double div=0.0;
        for(int i=0;i<n;i++){
            scores[i]=sc.nextInt();
            sum+=scores[i];
        }
        ave = (double)sum/(double)n;

        for(int i=0;i<n;i++){
            div += (Math.pow(scores[i]-ave,2))/n;
        }

        System.out.println(Math.pow(div, 0.5));
     } 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 ave=0.0; ave 0.0 double div=0.0; div 0.0 for(int i=0;i<n;i++){
            scores[i]=sc.nextInt();
            sum+=scores[i];
        } int i=0; int i=0; i 0 i<n i n 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 ave = (double)sum/(double)n ave (double)sum/(double)n (double)sum (double)n for(int i=0;i<n;i++){
            div += (Math.pow(scores[i]-ave,2))/n;
        } int i=0; int i=0; i 0 i<n i n i++ i++ i {
            div += (Math.pow(scores[i]-ave,2))/n;
        } {
            div += (Math.pow(scores[i]-ave,2))/n;
        } div += (Math.pow(scores[i]-ave,2))/n div (Math.pow(scores[i]-ave,2))/n (Math.pow(scores[i]-ave,2)) Math.pow Math scores[i]-ave scores[i] scores i ave 2 n System.out.println(Math.pow(div, 0.5)) System.out.println System.out System System.out Math.pow(div, 0.5) Math.pow Math div 0.5 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 scores[]=new int[n];
        int sum=0;
        double ave=0.0;
        double div=0.0;
        for(int i=0;i<n;i++){
            scores[i]=sc.nextInt();
            sum+=scores[i];
        }
        ave = (double)sum/(double)n;

        for(int i=0;i<n;i++){
            div += (Math.pow(scores[i]-ave,2))/n;
        }

        System.out.println(Math.pow(div, 0.5));
     }
        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 scores[]=new int[n];
        int sum=0;
        double ave=0.0;
        double div=0.0;
        for(int i=0;i<n;i++){
            scores[i]=sc.nextInt();
            sum+=scores[i];
        }
        ave = (double)sum/(double)n;

        for(int i=0;i<n;i++){
            div += (Math.pow(scores[i]-ave,2))/n;
        }

        System.out.println(Math.pow(div, 0.5));
     }
        sc.close();
        
    }   
} Main
import java.awt.print.Printable;
import java.util.Scanner;
import javax.sound.midi.SysexMessage;
import java.lang.Math;
  
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];
        int sum=0;
        double ave=0.0;
        double div=0.0;
        for(int i=0;i<n;i++){
            scores[i]=sc.nextInt();
            sum+=scores[i];
        }
        ave = (double)sum/(double)n;

        for(int i=0;i<n;i++){
            div += (Math.pow(scores[i]-ave,2))/n;
        }

        System.out.println(Math.pow(div, 0.5));
     }
        sc.close();
        
    }   
}
