import java.io.*;
class Main
{
    public static void main(String args[])throws IOException
    {
	BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
	
	String a;
	while(true)
	    {
		a=input.readLine();
		if(a.equals("0"))break;			
		int n=Integer.parseInt(a);
		String c=input.readLine();
		String b[]=c.split(" ");
		double d=0,sum=0;
		double e[]=new double[n];
		for(int j=0;j<n;j++)
		    {			
			e[j]=Double.parseDouble(b[j]);
			sum+=e[j];
		    }
		
			double m=sum/n;
			
			for(int i=0;i<n;i++)
			    {
				d+=(Math.pow((e[i]-m),2)/n);
			    } 
			
		System.out.println(Math.sqrt(d));
	    }
    }
}


			     import java.io.*; io.* java class Main
{
    public static void main(String args[])throws IOException
    {
	BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
	
	String a;
	while(true)
	    {
		a=input.readLine();
		if(a.equals("0"))break;			
		int n=Integer.parseInt(a);
		String c=input.readLine();
		String b[]=c.split(" ");
		double d=0,sum=0;
		double e[]=new double[n];
		for(int j=0;j<n;j++)
		    {			
			e[j]=Double.parseDouble(b[j]);
			sum+=e[j];
		    }
		
			double m=sum/n;
			
			for(int i=0;i<n;i++)
			    {
				d+=(Math.pow((e[i]-m),2)/n);
			    } 
			
		System.out.println(Math.sqrt(d));
	    }
    }
} Main public static void main(String args[])throws IOException
    {
	BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
	
	String a;
	while(true)
	    {
		a=input.readLine();
		if(a.equals("0"))break;			
		int n=Integer.parseInt(a);
		String c=input.readLine();
		String b[]=c.split(" ");
		double d=0,sum=0;
		double e[]=new double[n];
		for(int j=0;j<n;j++)
		    {			
			e[j]=Double.parseDouble(b[j]);
			sum+=e[j];
		    }
		
			double m=sum/n;
			
			for(int i=0;i<n;i++)
			    {
				d+=(Math.pow((e[i]-m),2)/n);
			    } 
			
		System.out.println(Math.sqrt(d));
	    }
    } main {
	BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
	
	String a;
	while(true)
	    {
		a=input.readLine();
		if(a.equals("0"))break;			
		int n=Integer.parseInt(a);
		String c=input.readLine();
		String b[]=c.split(" ");
		double d=0,sum=0;
		double e[]=new double[n];
		for(int j=0;j<n;j++)
		    {			
			e[j]=Double.parseDouble(b[j]);
			sum+=e[j];
		    }
		
			double m=sum/n;
			
			for(int i=0;i<n;i++)
			    {
				d+=(Math.pow((e[i]-m),2)/n);
			    } 
			
		System.out.println(Math.sqrt(d));
	    }
    } BufferedReader input=new BufferedReader(new InputStreamReader(System.in)); input new BufferedReader(new InputStreamReader(System.in)) String a; a while(true)
	    {
		a=input.readLine();
		if(a.equals("0"))break;			
		int n=Integer.parseInt(a);
		String c=input.readLine();
		String b[]=c.split(" ");
		double d=0,sum=0;
		double e[]=new double[n];
		for(int j=0;j<n;j++)
		    {			
			e[j]=Double.parseDouble(b[j]);
			sum+=e[j];
		    }
		
			double m=sum/n;
			
			for(int i=0;i<n;i++)
			    {
				d+=(Math.pow((e[i]-m),2)/n);
			    } 
			
		System.out.println(Math.sqrt(d));
	    } true {
		a=input.readLine();
		if(a.equals("0"))break;			
		int n=Integer.parseInt(a);
		String c=input.readLine();
		String b[]=c.split(" ");
		double d=0,sum=0;
		double e[]=new double[n];
		for(int j=0;j<n;j++)
		    {			
			e[j]=Double.parseDouble(b[j]);
			sum+=e[j];
		    }
		
			double m=sum/n;
			
			for(int i=0;i<n;i++)
			    {
				d+=(Math.pow((e[i]-m),2)/n);
			    } 
			
		System.out.println(Math.sqrt(d));
	    } a=input.readLine() a input.readLine() input.readLine input if(a.equals("0"))break; a.equals("0") a.equals a "0" break; int n=Integer.parseInt(a); n Integer.parseInt(a) Integer.parseInt Integer a String c=input.readLine(); c input.readLine() input.readLine input String b[]=c.split(" "); b c.split(" ") c.split c " " double d=0 d 0 sum=0; sum 0 double e[]=new double[n]; e new double[n] n for(int j=0;j<n;j++)
		    {			
			e[j]=Double.parseDouble(b[j]);
			sum+=e[j];
		    } int j=0; int j=0; j 0 j<n j n j++ j++ j {			
			e[j]=Double.parseDouble(b[j]);
			sum+=e[j];
		    } {			
			e[j]=Double.parseDouble(b[j]);
			sum+=e[j];
		    } e[j]=Double.parseDouble(b[j]) e[j] e j Double.parseDouble(b[j]) Double.parseDouble Double b[j] b j sum+=e[j] sum e[j] e j double m=sum/n; m sum/n sum n for(int i=0;i<n;i++)
			    {
				d+=(Math.pow((e[i]-m),2)/n);
			    } int i=0; int i=0; i 0 i<n i n i++ i++ i {
				d+=(Math.pow((e[i]-m),2)/n);
			    } {
				d+=(Math.pow((e[i]-m),2)/n);
			    } d+=(Math.pow((e[i]-m),2)/n) d (Math.pow((e[i]-m),2)/n) Math.pow((e[i]-m),2) Math.pow Math (e[i]-m) e[i] e i m 2 n System.out.println(Math.sqrt(d)) System.out.println System.out System System.out Math.sqrt(d) Math.sqrt Math d String args[] args
import java.io.*;
class Main
{
    public static void main(String args[])throws IOException
    {
	BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
	
	String a;
	while(true)
	    {
		a=input.readLine();
		if(a.equals("0"))break;			
		int n=Integer.parseInt(a);
		String c=input.readLine();
		String b[]=c.split(" ");
		double d=0,sum=0;
		double e[]=new double[n];
		for(int j=0;j<n;j++)
		    {			
			e[j]=Double.parseDouble(b[j]);
			sum+=e[j];
		    }
		
			double m=sum/n;
			
			for(int i=0;i<n;i++)
			    {
				d+=(Math.pow((e[i]-m),2)/n);
			    } 
			
		System.out.println(Math.sqrt(d));
	    }
    }
}


			    