import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		int n = 0;
	    double avg = 0;
		  
		while((n = Integer.parseInt(input.readLine())) != 0){
		  String line = input.readLine();
		  String[] str = line.split(" ");
		  double[] data = new double[n];
		  
		  double sum = 0 , scat = 0 , dev = 0;
		  for(int i = 0 ; i < n ; i ++){
			  data[i] = Double.parseDouble(str[i]);
			  sum += data[i];
			  avg = sum / (double)n ;
		  }
		  for(int j = 0 ; j < n ; j++){
			  scat += Math.pow(avg - data[j], 2); 
		  }
		  
		  dev = Math.sqrt(scat/(double)n);
		  sb.append(dev + "\n");
		  
		}
		System.out.print(sb);
		
	}

} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.IOException; IOException java.io public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		int n = 0;
	    double avg = 0;
		  
		while((n = Integer.parseInt(input.readLine())) != 0){
		  String line = input.readLine();
		  String[] str = line.split(" ");
		  double[] data = new double[n];
		  
		  double sum = 0 , scat = 0 , dev = 0;
		  for(int i = 0 ; i < n ; i ++){
			  data[i] = Double.parseDouble(str[i]);
			  sum += data[i];
			  avg = sum / (double)n ;
		  }
		  for(int j = 0 ; j < n ; j++){
			  scat += Math.pow(avg - data[j], 2); 
		  }
		  
		  dev = Math.sqrt(scat/(double)n);
		  sb.append(dev + "\n");
		  
		}
		System.out.print(sb);
		
	}

} Main public static void main(String[] args) throws IOException {
		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		int n = 0;
	    double avg = 0;
		  
		while((n = Integer.parseInt(input.readLine())) != 0){
		  String line = input.readLine();
		  String[] str = line.split(" ");
		  double[] data = new double[n];
		  
		  double sum = 0 , scat = 0 , dev = 0;
		  for(int i = 0 ; i < n ; i ++){
			  data[i] = Double.parseDouble(str[i]);
			  sum += data[i];
			  avg = sum / (double)n ;
		  }
		  for(int j = 0 ; j < n ; j++){
			  scat += Math.pow(avg - data[j], 2); 
		  }
		  
		  dev = Math.sqrt(scat/(double)n);
		  sb.append(dev + "\n");
		  
		}
		System.out.print(sb);
		
	} main {
		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		int n = 0;
	    double avg = 0;
		  
		while((n = Integer.parseInt(input.readLine())) != 0){
		  String line = input.readLine();
		  String[] str = line.split(" ");
		  double[] data = new double[n];
		  
		  double sum = 0 , scat = 0 , dev = 0;
		  for(int i = 0 ; i < n ; i ++){
			  data[i] = Double.parseDouble(str[i]);
			  sum += data[i];
			  avg = sum / (double)n ;
		  }
		  for(int j = 0 ; j < n ; j++){
			  scat += Math.pow(avg - data[j], 2); 
		  }
		  
		  dev = Math.sqrt(scat/(double)n);
		  sb.append(dev + "\n");
		  
		}
		System.out.print(sb);
		
	} BufferedReader input = new BufferedReader(new InputStreamReader(System.in)); input new BufferedReader(new InputStreamReader(System.in)) StringBuilder sb = new StringBuilder(); sb new StringBuilder() int n = 0; n 0 double avg = 0; avg 0 while((n = Integer.parseInt(input.readLine())) != 0){
		  String line = input.readLine();
		  String[] str = line.split(" ");
		  double[] data = new double[n];
		  
		  double sum = 0 , scat = 0 , dev = 0;
		  for(int i = 0 ; i < n ; i ++){
			  data[i] = Double.parseDouble(str[i]);
			  sum += data[i];
			  avg = sum / (double)n ;
		  }
		  for(int j = 0 ; j < n ; j++){
			  scat += Math.pow(avg - data[j], 2); 
		  }
		  
		  dev = Math.sqrt(scat/(double)n);
		  sb.append(dev + "\n");
		  
		} (n = Integer.parseInt(input.readLine())) != 0 (n = Integer.parseInt(input.readLine())) n Integer.parseInt(input.readLine()) Integer.parseInt Integer input.readLine() input.readLine input 0 {
		  String line = input.readLine();
		  String[] str = line.split(" ");
		  double[] data = new double[n];
		  
		  double sum = 0 , scat = 0 , dev = 0;
		  for(int i = 0 ; i < n ; i ++){
			  data[i] = Double.parseDouble(str[i]);
			  sum += data[i];
			  avg = sum / (double)n ;
		  }
		  for(int j = 0 ; j < n ; j++){
			  scat += Math.pow(avg - data[j], 2); 
		  }
		  
		  dev = Math.sqrt(scat/(double)n);
		  sb.append(dev + "\n");
		  
		} String line = input.readLine(); line input.readLine() input.readLine input String[] str = line.split(" "); str line.split(" ") line.split line " " double[] data = new double[n]; data new double[n] n double sum = 0 sum 0 scat = 0 scat 0 dev = 0; dev 0 for(int i = 0 ; i < n ; i ++){
			  data[i] = Double.parseDouble(str[i]);
			  sum += data[i];
			  avg = sum / (double)n ;
		  } int i = 0 ; int i = 0 ; i 0 i < n i n i ++ i ++ i {
			  data[i] = Double.parseDouble(str[i]);
			  sum += data[i];
			  avg = sum / (double)n ;
		  } {
			  data[i] = Double.parseDouble(str[i]);
			  sum += data[i];
			  avg = sum / (double)n ;
		  } data[i] = Double.parseDouble(str[i]) data[i] data i Double.parseDouble(str[i]) Double.parseDouble Double str[i] str i sum += data[i] sum data[i] data i avg = sum / (double)n avg sum / (double)n sum (double)n for(int j = 0 ; j < n ; j++){
			  scat += Math.pow(avg - data[j], 2); 
		  } int j = 0 ; int j = 0 ; j 0 j < n j n j++ j++ j {
			  scat += Math.pow(avg - data[j], 2); 
		  } {
			  scat += Math.pow(avg - data[j], 2); 
		  } scat += Math.pow(avg - data[j], 2) scat Math.pow(avg - data[j], 2) Math.pow Math avg - data[j] avg data[j] data j 2 dev = Math.sqrt(scat/(double)n) dev Math.sqrt(scat/(double)n) Math.sqrt Math scat/(double)n scat (double)n sb.append(dev + "\n") sb.append sb dev + "\n" dev "\n" System.out.print(sb) System.out.print System.out System System.out sb String[] args args public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		int n = 0;
	    double avg = 0;
		  
		while((n = Integer.parseInt(input.readLine())) != 0){
		  String line = input.readLine();
		  String[] str = line.split(" ");
		  double[] data = new double[n];
		  
		  double sum = 0 , scat = 0 , dev = 0;
		  for(int i = 0 ; i < n ; i ++){
			  data[i] = Double.parseDouble(str[i]);
			  sum += data[i];
			  avg = sum / (double)n ;
		  }
		  for(int j = 0 ; j < n ; j++){
			  scat += Math.pow(avg - data[j], 2); 
		  }
		  
		  dev = Math.sqrt(scat/(double)n);
		  sb.append(dev + "\n");
		  
		}
		System.out.print(sb);
		
	}

} public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		int n = 0;
	    double avg = 0;
		  
		while((n = Integer.parseInt(input.readLine())) != 0){
		  String line = input.readLine();
		  String[] str = line.split(" ");
		  double[] data = new double[n];
		  
		  double sum = 0 , scat = 0 , dev = 0;
		  for(int i = 0 ; i < n ; i ++){
			  data[i] = Double.parseDouble(str[i]);
			  sum += data[i];
			  avg = sum / (double)n ;
		  }
		  for(int j = 0 ; j < n ; j++){
			  scat += Math.pow(avg - data[j], 2); 
		  }
		  
		  dev = Math.sqrt(scat/(double)n);
		  sb.append(dev + "\n");
		  
		}
		System.out.print(sb);
		
	}

} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		int n = 0;
	    double avg = 0;
		  
		while((n = Integer.parseInt(input.readLine())) != 0){
		  String line = input.readLine();
		  String[] str = line.split(" ");
		  double[] data = new double[n];
		  
		  double sum = 0 , scat = 0 , dev = 0;
		  for(int i = 0 ; i < n ; i ++){
			  data[i] = Double.parseDouble(str[i]);
			  sum += data[i];
			  avg = sum / (double)n ;
		  }
		  for(int j = 0 ; j < n ; j++){
			  scat += Math.pow(avg - data[j], 2); 
		  }
		  
		  dev = Math.sqrt(scat/(double)n);
		  sb.append(dev + "\n");
		  
		}
		System.out.print(sb);
		
	}

}