import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.text.DecimalFormat;

public class Main {
	public static void main(String[] args)throws Exception{
		InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
    
        
        DecimalFormat df = new DecimalFormat("0.00000");
        while (true)
        {
        	int n = Integer.parseInt(br.readLine());
        	if (n == 0)
        		break;
        	String[] tensu = br.readLine().split(" ");
        	
        	double sum = 0;
        	double asum = 0;
        	double average = 0;
        	double hensa = 0;
        	for (int i = 0; i < n; i++)
        	{
        		sum += Double.parseDouble(tensu[i]);
        	}
        	average = sum / n;
        	for (int i = 0; i < n; i++)
        	{
        		asum += Math.pow(Double.parseDouble(tensu[i]) - average, 2);
        	}
        	
        	hensa = Math.sqrt(asum / n);
        	System.out.println(df.format(hensa));
        }
    	
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.text.DecimalFormat; DecimalFormat java.text public class Main {
	public static void main(String[] args)throws Exception{
		InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
    
        
        DecimalFormat df = new DecimalFormat("0.00000");
        while (true)
        {
        	int n = Integer.parseInt(br.readLine());
        	if (n == 0)
        		break;
        	String[] tensu = br.readLine().split(" ");
        	
        	double sum = 0;
        	double asum = 0;
        	double average = 0;
        	double hensa = 0;
        	for (int i = 0; i < n; i++)
        	{
        		sum += Double.parseDouble(tensu[i]);
        	}
        	average = sum / n;
        	for (int i = 0; i < n; i++)
        	{
        		asum += Math.pow(Double.parseDouble(tensu[i]) - average, 2);
        	}
        	
        	hensa = Math.sqrt(asum / n);
        	System.out.println(df.format(hensa));
        }
    	
	}
} Main public static void main(String[] args)throws Exception{
		InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
    
        
        DecimalFormat df = new DecimalFormat("0.00000");
        while (true)
        {
        	int n = Integer.parseInt(br.readLine());
        	if (n == 0)
        		break;
        	String[] tensu = br.readLine().split(" ");
        	
        	double sum = 0;
        	double asum = 0;
        	double average = 0;
        	double hensa = 0;
        	for (int i = 0; i < n; i++)
        	{
        		sum += Double.parseDouble(tensu[i]);
        	}
        	average = sum / n;
        	for (int i = 0; i < n; i++)
        	{
        		asum += Math.pow(Double.parseDouble(tensu[i]) - average, 2);
        	}
        	
        	hensa = Math.sqrt(asum / n);
        	System.out.println(df.format(hensa));
        }
    	
	} main {
		InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
    
        
        DecimalFormat df = new DecimalFormat("0.00000");
        while (true)
        {
        	int n = Integer.parseInt(br.readLine());
        	if (n == 0)
        		break;
        	String[] tensu = br.readLine().split(" ");
        	
        	double sum = 0;
        	double asum = 0;
        	double average = 0;
        	double hensa = 0;
        	for (int i = 0; i < n; i++)
        	{
        		sum += Double.parseDouble(tensu[i]);
        	}
        	average = sum / n;
        	for (int i = 0; i < n; i++)
        	{
        		asum += Math.pow(Double.parseDouble(tensu[i]) - average, 2);
        	}
        	
        	hensa = Math.sqrt(asum / n);
        	System.out.println(df.format(hensa));
        }
    	
	} InputStreamReader isr = new InputStreamReader(System.in); isr new InputStreamReader(System.in) BufferedReader br = new BufferedReader(isr); br new BufferedReader(isr) DecimalFormat df = new DecimalFormat("0.00000"); df new DecimalFormat("0.00000") while (true)
        {
        	int n = Integer.parseInt(br.readLine());
        	if (n == 0)
        		break;
        	String[] tensu = br.readLine().split(" ");
        	
        	double sum = 0;
        	double asum = 0;
        	double average = 0;
        	double hensa = 0;
        	for (int i = 0; i < n; i++)
        	{
        		sum += Double.parseDouble(tensu[i]);
        	}
        	average = sum / n;
        	for (int i = 0; i < n; i++)
        	{
        		asum += Math.pow(Double.parseDouble(tensu[i]) - average, 2);
        	}
        	
        	hensa = Math.sqrt(asum / n);
        	System.out.println(df.format(hensa));
        } true {
        	int n = Integer.parseInt(br.readLine());
        	if (n == 0)
        		break;
        	String[] tensu = br.readLine().split(" ");
        	
        	double sum = 0;
        	double asum = 0;
        	double average = 0;
        	double hensa = 0;
        	for (int i = 0; i < n; i++)
        	{
        		sum += Double.parseDouble(tensu[i]);
        	}
        	average = sum / n;
        	for (int i = 0; i < n; i++)
        	{
        		asum += Math.pow(Double.parseDouble(tensu[i]) - average, 2);
        	}
        	
        	hensa = Math.sqrt(asum / n);
        	System.out.println(df.format(hensa));
        } int n = Integer.parseInt(br.readLine()); n Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br if (n == 0)
        		break; n == 0 n 0 break; String[] tensu = br.readLine().split(" "); tensu br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " double sum = 0; sum 0 double asum = 0; asum 0 double average = 0; average 0 double hensa = 0; hensa 0 for (int i = 0; i < n; i++)
        	{
        		sum += Double.parseDouble(tensu[i]);
        	} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
        		sum += Double.parseDouble(tensu[i]);
        	} {
        		sum += Double.parseDouble(tensu[i]);
        	} sum += Double.parseDouble(tensu[i]) sum Double.parseDouble(tensu[i]) Double.parseDouble Double tensu[i] tensu i average = sum / n average sum / n sum n for (int i = 0; i < n; i++)
        	{
        		asum += Math.pow(Double.parseDouble(tensu[i]) - average, 2);
        	} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
        		asum += Math.pow(Double.parseDouble(tensu[i]) - average, 2);
        	} {
        		asum += Math.pow(Double.parseDouble(tensu[i]) - average, 2);
        	} asum += Math.pow(Double.parseDouble(tensu[i]) - average, 2) asum Math.pow(Double.parseDouble(tensu[i]) - average, 2) Math.pow Math Double.parseDouble(tensu[i]) - average Double.parseDouble(tensu[i]) Double.parseDouble Double tensu[i] tensu i average 2 hensa = Math.sqrt(asum / n) hensa Math.sqrt(asum / n) Math.sqrt Math asum / n asum n System.out.println(df.format(hensa)) System.out.println System.out System System.out df.format(hensa) df.format df hensa String[] args args public class Main {
	public static void main(String[] args)throws Exception{
		InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
    
        
        DecimalFormat df = new DecimalFormat("0.00000");
        while (true)
        {
        	int n = Integer.parseInt(br.readLine());
        	if (n == 0)
        		break;
        	String[] tensu = br.readLine().split(" ");
        	
        	double sum = 0;
        	double asum = 0;
        	double average = 0;
        	double hensa = 0;
        	for (int i = 0; i < n; i++)
        	{
        		sum += Double.parseDouble(tensu[i]);
        	}
        	average = sum / n;
        	for (int i = 0; i < n; i++)
        	{
        		asum += Math.pow(Double.parseDouble(tensu[i]) - average, 2);
        	}
        	
        	hensa = Math.sqrt(asum / n);
        	System.out.println(df.format(hensa));
        }
    	
	}
} public class Main {
	public static void main(String[] args)throws Exception{
		InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
    
        
        DecimalFormat df = new DecimalFormat("0.00000");
        while (true)
        {
        	int n = Integer.parseInt(br.readLine());
        	if (n == 0)
        		break;
        	String[] tensu = br.readLine().split(" ");
        	
        	double sum = 0;
        	double asum = 0;
        	double average = 0;
        	double hensa = 0;
        	for (int i = 0; i < n; i++)
        	{
        		sum += Double.parseDouble(tensu[i]);
        	}
        	average = sum / n;
        	for (int i = 0; i < n; i++)
        	{
        		asum += Math.pow(Double.parseDouble(tensu[i]) - average, 2);
        	}
        	
        	hensa = Math.sqrt(asum / n);
        	System.out.println(df.format(hensa));
        }
    	
	}
} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.text.DecimalFormat;

public class Main {
	public static void main(String[] args)throws Exception{
		InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
    
        
        DecimalFormat df = new DecimalFormat("0.00000");
        while (true)
        {
        	int n = Integer.parseInt(br.readLine());
        	if (n == 0)
        		break;
        	String[] tensu = br.readLine().split(" ");
        	
        	double sum = 0;
        	double asum = 0;
        	double average = 0;
        	double hensa = 0;
        	for (int i = 0; i < n; i++)
        	{
        		sum += Double.parseDouble(tensu[i]);
        	}
        	average = sum / n;
        	for (int i = 0; i < n; i++)
        	{
        		asum += Math.pow(Double.parseDouble(tensu[i]) - average, 2);
        	}
        	
        	hensa = Math.sqrt(asum / n);
        	System.out.println(df.format(hensa));
        }
    	
	}
}