import java.util.Scanner;
import java.io.*;

class Main {
    public static void main(String[] args)throws IOException{ 
    	InputStreamReader in = new InputStreamReader(System.in);
        BufferedReader read = new BufferedReader(in);

        int num,count;
        
        while(true){
        	num = Integer.parseInt(read.readLine());
        	if(num == 0){
        		break;
        	}
        	else{
        		double sum = 0;
                double ave = 0;
                double sum2 = 0;
                double a2 = 0;
                double deviation = 0;
        		
        		String line = read.readLine();    
        		String [] spli = line.split(" ");
        		double [] x = new double [num];
        		
        		for(count = 0; count < num; count++){
        			x[count] = Double.parseDouble(spli[count]);
        			sum = sum + x[count];     			
        		}  
        		ave = sum/num;
        		for(count = 0; count < num; count++){
        			sum2 = sum2 + (ave-x[count])*(ave-x[count]);
        		}
        		a2 = sum2/num;
        		deviation = Math.sqrt(a2);
        		System.out.println(deviation);
        	}	
        }
    }
} import java.util.Scanner; Scanner java.util import java.io.*; io.* java class Main {
    public static void main(String[] args)throws IOException{ 
    	InputStreamReader in = new InputStreamReader(System.in);
        BufferedReader read = new BufferedReader(in);

        int num,count;
        
        while(true){
        	num = Integer.parseInt(read.readLine());
        	if(num == 0){
        		break;
        	}
        	else{
        		double sum = 0;
                double ave = 0;
                double sum2 = 0;
                double a2 = 0;
                double deviation = 0;
        		
        		String line = read.readLine();    
        		String [] spli = line.split(" ");
        		double [] x = new double [num];
        		
        		for(count = 0; count < num; count++){
        			x[count] = Double.parseDouble(spli[count]);
        			sum = sum + x[count];     			
        		}  
        		ave = sum/num;
        		for(count = 0; count < num; count++){
        			sum2 = sum2 + (ave-x[count])*(ave-x[count]);
        		}
        		a2 = sum2/num;
        		deviation = Math.sqrt(a2);
        		System.out.println(deviation);
        	}	
        }
    }
} Main public static void main(String[] args)throws IOException{ 
    	InputStreamReader in = new InputStreamReader(System.in);
        BufferedReader read = new BufferedReader(in);

        int num,count;
        
        while(true){
        	num = Integer.parseInt(read.readLine());
        	if(num == 0){
        		break;
        	}
        	else{
        		double sum = 0;
                double ave = 0;
                double sum2 = 0;
                double a2 = 0;
                double deviation = 0;
        		
        		String line = read.readLine();    
        		String [] spli = line.split(" ");
        		double [] x = new double [num];
        		
        		for(count = 0; count < num; count++){
        			x[count] = Double.parseDouble(spli[count]);
        			sum = sum + x[count];     			
        		}  
        		ave = sum/num;
        		for(count = 0; count < num; count++){
        			sum2 = sum2 + (ave-x[count])*(ave-x[count]);
        		}
        		a2 = sum2/num;
        		deviation = Math.sqrt(a2);
        		System.out.println(deviation);
        	}	
        }
    } main { 
    	InputStreamReader in = new InputStreamReader(System.in);
        BufferedReader read = new BufferedReader(in);

        int num,count;
        
        while(true){
        	num = Integer.parseInt(read.readLine());
        	if(num == 0){
        		break;
        	}
        	else{
        		double sum = 0;
                double ave = 0;
                double sum2 = 0;
                double a2 = 0;
                double deviation = 0;
        		
        		String line = read.readLine();    
        		String [] spli = line.split(" ");
        		double [] x = new double [num];
        		
        		for(count = 0; count < num; count++){
        			x[count] = Double.parseDouble(spli[count]);
        			sum = sum + x[count];     			
        		}  
        		ave = sum/num;
        		for(count = 0; count < num; count++){
        			sum2 = sum2 + (ave-x[count])*(ave-x[count]);
        		}
        		a2 = sum2/num;
        		deviation = Math.sqrt(a2);
        		System.out.println(deviation);
        	}	
        }
    } InputStreamReader in = new InputStreamReader(System.in); in new InputStreamReader(System.in) BufferedReader read = new BufferedReader(in); read new BufferedReader(in) int num num count; count while(true){
        	num = Integer.parseInt(read.readLine());
        	if(num == 0){
        		break;
        	}
        	else{
        		double sum = 0;
                double ave = 0;
                double sum2 = 0;
                double a2 = 0;
                double deviation = 0;
        		
        		String line = read.readLine();    
        		String [] spli = line.split(" ");
        		double [] x = new double [num];
        		
        		for(count = 0; count < num; count++){
        			x[count] = Double.parseDouble(spli[count]);
        			sum = sum + x[count];     			
        		}  
        		ave = sum/num;
        		for(count = 0; count < num; count++){
        			sum2 = sum2 + (ave-x[count])*(ave-x[count]);
        		}
        		a2 = sum2/num;
        		deviation = Math.sqrt(a2);
        		System.out.println(deviation);
        	}	
        } true {
        	num = Integer.parseInt(read.readLine());
        	if(num == 0){
        		break;
        	}
        	else{
        		double sum = 0;
                double ave = 0;
                double sum2 = 0;
                double a2 = 0;
                double deviation = 0;
        		
        		String line = read.readLine();    
        		String [] spli = line.split(" ");
        		double [] x = new double [num];
        		
        		for(count = 0; count < num; count++){
        			x[count] = Double.parseDouble(spli[count]);
        			sum = sum + x[count];     			
        		}  
        		ave = sum/num;
        		for(count = 0; count < num; count++){
        			sum2 = sum2 + (ave-x[count])*(ave-x[count]);
        		}
        		a2 = sum2/num;
        		deviation = Math.sqrt(a2);
        		System.out.println(deviation);
        	}	
        } num = Integer.parseInt(read.readLine()) num Integer.parseInt(read.readLine()) Integer.parseInt Integer read.readLine() read.readLine read if(num == 0){
        		break;
        	}
        	else{
        		double sum = 0;
                double ave = 0;
                double sum2 = 0;
                double a2 = 0;
                double deviation = 0;
        		
        		String line = read.readLine();    
        		String [] spli = line.split(" ");
        		double [] x = new double [num];
        		
        		for(count = 0; count < num; count++){
        			x[count] = Double.parseDouble(spli[count]);
        			sum = sum + x[count];     			
        		}  
        		ave = sum/num;
        		for(count = 0; count < num; count++){
        			sum2 = sum2 + (ave-x[count])*(ave-x[count]);
        		}
        		a2 = sum2/num;
        		deviation = Math.sqrt(a2);
        		System.out.println(deviation);
        	} num == 0 num 0 {
        		break;
        	} break; {
        		double sum = 0;
                double ave = 0;
                double sum2 = 0;
                double a2 = 0;
                double deviation = 0;
        		
        		String line = read.readLine();    
        		String [] spli = line.split(" ");
        		double [] x = new double [num];
        		
        		for(count = 0; count < num; count++){
        			x[count] = Double.parseDouble(spli[count]);
        			sum = sum + x[count];     			
        		}  
        		ave = sum/num;
        		for(count = 0; count < num; count++){
        			sum2 = sum2 + (ave-x[count])*(ave-x[count]);
        		}
        		a2 = sum2/num;
        		deviation = Math.sqrt(a2);
        		System.out.println(deviation);
        	} double sum = 0; sum 0 double ave = 0; ave 0 double sum2 = 0; sum2 0 double a2 = 0; a2 0 double deviation = 0; deviation 0 String line = read.readLine(); line read.readLine() read.readLine read String [] spli = line.split(" "); spli line.split(" ") line.split line " " double [] x = new double [num]; x new double [num] num for(count = 0; count < num; count++){
        			x[count] = Double.parseDouble(spli[count]);
        			sum = sum + x[count];     			
        		} count = 0; count = 0 count 0 count < num count num count++ count++ count {
        			x[count] = Double.parseDouble(spli[count]);
        			sum = sum + x[count];     			
        		} {
        			x[count] = Double.parseDouble(spli[count]);
        			sum = sum + x[count];     			
        		} x[count] = Double.parseDouble(spli[count]) x[count] x count Double.parseDouble(spli[count]) Double.parseDouble Double spli[count] spli count sum = sum + x[count] sum sum + x[count] sum x[count] x count ave = sum/num ave sum/num sum num for(count = 0; count < num; count++){
        			sum2 = sum2 + (ave-x[count])*(ave-x[count]);
        		} count = 0; count = 0 count 0 count < num count num count++ count++ count {
        			sum2 = sum2 + (ave-x[count])*(ave-x[count]);
        		} {
        			sum2 = sum2 + (ave-x[count])*(ave-x[count]);
        		} sum2 = sum2 + (ave-x[count])*(ave-x[count]) sum2 sum2 + (ave-x[count])*(ave-x[count]) sum2 (ave-x[count])*(ave-x[count]) (ave-x[count]) ave x[count] x count (ave-x[count]) ave x[count] x count a2 = sum2/num a2 sum2/num sum2 num deviation = Math.sqrt(a2) deviation Math.sqrt(a2) Math.sqrt Math a2 System.out.println(deviation) System.out.println System.out System System.out deviation String[] args args
import java.util.Scanner;
import java.io.*;

class Main {
    public static void main(String[] args)throws IOException{ 
    	InputStreamReader in = new InputStreamReader(System.in);
        BufferedReader read = new BufferedReader(in);

        int num,count;
        
        while(true){
        	num = Integer.parseInt(read.readLine());
        	if(num == 0){
        		break;
        	}
        	else{
        		double sum = 0;
                double ave = 0;
                double sum2 = 0;
                double a2 = 0;
                double deviation = 0;
        		
        		String line = read.readLine();    
        		String [] spli = line.split(" ");
        		double [] x = new double [num];
        		
        		for(count = 0; count < num; count++){
        			x[count] = Double.parseDouble(spli[count]);
        			sum = sum + x[count];     			
        		}  
        		ave = sum/num;
        		for(count = 0; count < num; count++){
        			sum2 = sum2 + (ave-x[count])*(ave-x[count]);
        		}
        		a2 = sum2/num;
        		deviation = Math.sqrt(a2);
        		System.out.println(deviation);
        	}	
        }
    }
}