import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;

class Main {
	public static void main(String[] args) throws NumberFormatException, IOException {
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        int n=Integer.parseInt(br.readLine());
        while(!(n==0)){
        String str=br.readLine();
        int[] in=new int[n];double sum=0;
        Scanner sc=new Scanner(str);
        for(int i=0;i<n;i++){
        	
        	in[i]=sc.nextInt();
        	sum+=in[i];
        	  }
        double m=sum/n;
        
        
        double t=0;
        for(int i:in){
       	t+=Math.pow(i-m,2);
        	
        }
        double ar=Math.sqrt(t/n);
        System.out.printf("%.8f%n",ar);
        n=Integer.parseInt(br.readLine());
}
}} import java.io.BufferedReader; BufferedReader java.io import java.io.FileInputStream; FileInputStream java.io import java.io.FileReader; FileReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.util.Scanner; Scanner java.util class Main {
	public static void main(String[] args) throws NumberFormatException, IOException {
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        int n=Integer.parseInt(br.readLine());
        while(!(n==0)){
        String str=br.readLine();
        int[] in=new int[n];double sum=0;
        Scanner sc=new Scanner(str);
        for(int i=0;i<n;i++){
        	
        	in[i]=sc.nextInt();
        	sum+=in[i];
        	  }
        double m=sum/n;
        
        
        double t=0;
        for(int i:in){
       	t+=Math.pow(i-m,2);
        	
        }
        double ar=Math.sqrt(t/n);
        System.out.printf("%.8f%n",ar);
        n=Integer.parseInt(br.readLine());
}
}} Main public static void main(String[] args) throws NumberFormatException, IOException {
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        int n=Integer.parseInt(br.readLine());
        while(!(n==0)){
        String str=br.readLine();
        int[] in=new int[n];double sum=0;
        Scanner sc=new Scanner(str);
        for(int i=0;i<n;i++){
        	
        	in[i]=sc.nextInt();
        	sum+=in[i];
        	  }
        double m=sum/n;
        
        
        double t=0;
        for(int i:in){
       	t+=Math.pow(i-m,2);
        	
        }
        double ar=Math.sqrt(t/n);
        System.out.printf("%.8f%n",ar);
        n=Integer.parseInt(br.readLine());
}
} main {
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        int n=Integer.parseInt(br.readLine());
        while(!(n==0)){
        String str=br.readLine();
        int[] in=new int[n];double sum=0;
        Scanner sc=new Scanner(str);
        for(int i=0;i<n;i++){
        	
        	in[i]=sc.nextInt();
        	sum+=in[i];
        	  }
        double m=sum/n;
        
        
        double t=0;
        for(int i:in){
       	t+=Math.pow(i-m,2);
        	
        }
        double ar=Math.sqrt(t/n);
        System.out.printf("%.8f%n",ar);
        n=Integer.parseInt(br.readLine());
}
} BufferedReader br=new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int n=Integer.parseInt(br.readLine()); n Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br while(!(n==0)){
        String str=br.readLine();
        int[] in=new int[n];double sum=0;
        Scanner sc=new Scanner(str);
        for(int i=0;i<n;i++){
        	
        	in[i]=sc.nextInt();
        	sum+=in[i];
        	  }
        double m=sum/n;
        
        
        double t=0;
        for(int i:in){
       	t+=Math.pow(i-m,2);
        	
        }
        double ar=Math.sqrt(t/n);
        System.out.printf("%.8f%n",ar);
        n=Integer.parseInt(br.readLine());
} !(n==0) (n==0) n 0 {
        String str=br.readLine();
        int[] in=new int[n];double sum=0;
        Scanner sc=new Scanner(str);
        for(int i=0;i<n;i++){
        	
        	in[i]=sc.nextInt();
        	sum+=in[i];
        	  }
        double m=sum/n;
        
        
        double t=0;
        for(int i:in){
       	t+=Math.pow(i-m,2);
        	
        }
        double ar=Math.sqrt(t/n);
        System.out.printf("%.8f%n",ar);
        n=Integer.parseInt(br.readLine());
} String str=br.readLine(); str br.readLine() br.readLine br int[] in=new int[n]; in new int[n] n double sum=0; sum 0 Scanner sc=new Scanner(str); sc new Scanner(str) for(int i=0;i<n;i++){
        	
        	in[i]=sc.nextInt();
        	sum+=in[i];
        	  } int i=0; int i=0; i 0 i<n i n i++ i++ i {
        	
        	in[i]=sc.nextInt();
        	sum+=in[i];
        	  } {
        	
        	in[i]=sc.nextInt();
        	sum+=in[i];
        	  } in[i]=sc.nextInt() in[i] in i sc.nextInt() sc.nextInt sc sum+=in[i] sum in[i] in i double m=sum/n; m sum/n sum n double t=0; t 0 for(int i:in){
       	t+=Math.pow(i-m,2);
        	
        } int i in {
       	t+=Math.pow(i-m,2);
        	
        } {
       	t+=Math.pow(i-m,2);
        	
        } t+=Math.pow(i-m,2) t Math.pow(i-m,2) Math.pow Math i-m i m 2 double ar=Math.sqrt(t/n); ar Math.sqrt(t/n) Math.sqrt Math t/n t n System.out.printf("%.8f%n",ar) System.out.printf System.out System System.out "%.8f%n" ar n=Integer.parseInt(br.readLine()) n Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br String[] args args
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;

class Main {
	public static void main(String[] args) throws NumberFormatException, IOException {
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        int n=Integer.parseInt(br.readLine());
        while(!(n==0)){
        String str=br.readLine();
        int[] in=new int[n];double sum=0;
        Scanner sc=new Scanner(str);
        for(int i=0;i<n;i++){
        	
        	in[i]=sc.nextInt();
        	sum+=in[i];
        	  }
        double m=sum/n;
        
        
        double t=0;
        for(int i:in){
       	t+=Math.pow(i-m,2);
        	
        }
        double ar=Math.sqrt(t/n);
        System.out.printf("%.8f%n",ar);
        n=Integer.parseInt(br.readLine());
}
}}