import java.util.Scanner;

public class Main {
	  public static void main(String[]args){
		    Scanner sc = new Scanner(System.in);
		    int ten[];
		    int i=0;
		    int sum;
		    double m=0.0;
		    double x=0.0;
		    double A=0.0;
		    ten = new int[1000];
		    while(true)
            {
		    	sum=0;
		    	m=0.0;
			    x=0.0;
			    A=0.0;
		    	int n=sc.nextInt();
                        if(n==0) break;
		    	for(i=0;i<n;++i)
		    	{
		    		ten[i]=sc.nextInt();
		    		sum=sum+ten[i];
		    	}
		    	m=(double)sum/(double)n;
		    	for(i=0;i<n;++i)
		    	{
		    		x=x+(ten[i]-m)*(ten[i]-m);
		    	}
		    	A=x/(double)n;
		    	double a=Math.sqrt(A);
		    	System.out.println(a);
            }
		    	sc.close();
		    }
}
 import java.util.Scanner; Scanner java.util public class Main {
	  public static void main(String[]args){
		    Scanner sc = new Scanner(System.in);
		    int ten[];
		    int i=0;
		    int sum;
		    double m=0.0;
		    double x=0.0;
		    double A=0.0;
		    ten = new int[1000];
		    while(true)
            {
		    	sum=0;
		    	m=0.0;
			    x=0.0;
			    A=0.0;
		    	int n=sc.nextInt();
                        if(n==0) break;
		    	for(i=0;i<n;++i)
		    	{
		    		ten[i]=sc.nextInt();
		    		sum=sum+ten[i];
		    	}
		    	m=(double)sum/(double)n;
		    	for(i=0;i<n;++i)
		    	{
		    		x=x+(ten[i]-m)*(ten[i]-m);
		    	}
		    	A=x/(double)n;
		    	double a=Math.sqrt(A);
		    	System.out.println(a);
            }
		    	sc.close();
		    }
} Main public static void main(String[]args){
		    Scanner sc = new Scanner(System.in);
		    int ten[];
		    int i=0;
		    int sum;
		    double m=0.0;
		    double x=0.0;
		    double A=0.0;
		    ten = new int[1000];
		    while(true)
            {
		    	sum=0;
		    	m=0.0;
			    x=0.0;
			    A=0.0;
		    	int n=sc.nextInt();
                        if(n==0) break;
		    	for(i=0;i<n;++i)
		    	{
		    		ten[i]=sc.nextInt();
		    		sum=sum+ten[i];
		    	}
		    	m=(double)sum/(double)n;
		    	for(i=0;i<n;++i)
		    	{
		    		x=x+(ten[i]-m)*(ten[i]-m);
		    	}
		    	A=x/(double)n;
		    	double a=Math.sqrt(A);
		    	System.out.println(a);
            }
		    	sc.close();
		    } main {
		    Scanner sc = new Scanner(System.in);
		    int ten[];
		    int i=0;
		    int sum;
		    double m=0.0;
		    double x=0.0;
		    double A=0.0;
		    ten = new int[1000];
		    while(true)
            {
		    	sum=0;
		    	m=0.0;
			    x=0.0;
			    A=0.0;
		    	int n=sc.nextInt();
                        if(n==0) break;
		    	for(i=0;i<n;++i)
		    	{
		    		ten[i]=sc.nextInt();
		    		sum=sum+ten[i];
		    	}
		    	m=(double)sum/(double)n;
		    	for(i=0;i<n;++i)
		    	{
		    		x=x+(ten[i]-m)*(ten[i]-m);
		    	}
		    	A=x/(double)n;
		    	double a=Math.sqrt(A);
		    	System.out.println(a);
            }
		    	sc.close();
		    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int ten[]; ten int i=0; i 0 int sum; sum double m=0.0; m 0.0 double x=0.0; x 0.0 double A=0.0; A 0.0 ten = new int[1000] ten new int[1000] 1000 while(true)
            {
		    	sum=0;
		    	m=0.0;
			    x=0.0;
			    A=0.0;
		    	int n=sc.nextInt();
                        if(n==0) break;
		    	for(i=0;i<n;++i)
		    	{
		    		ten[i]=sc.nextInt();
		    		sum=sum+ten[i];
		    	}
		    	m=(double)sum/(double)n;
		    	for(i=0;i<n;++i)
		    	{
		    		x=x+(ten[i]-m)*(ten[i]-m);
		    	}
		    	A=x/(double)n;
		    	double a=Math.sqrt(A);
		    	System.out.println(a);
            } true {
		    	sum=0;
		    	m=0.0;
			    x=0.0;
			    A=0.0;
		    	int n=sc.nextInt();
                        if(n==0) break;
		    	for(i=0;i<n;++i)
		    	{
		    		ten[i]=sc.nextInt();
		    		sum=sum+ten[i];
		    	}
		    	m=(double)sum/(double)n;
		    	for(i=0;i<n;++i)
		    	{
		    		x=x+(ten[i]-m)*(ten[i]-m);
		    	}
		    	A=x/(double)n;
		    	double a=Math.sqrt(A);
		    	System.out.println(a);
            } sum=0 sum 0 m=0.0 m 0.0 x=0.0 x 0.0 A=0.0 A 0.0 int n=sc.nextInt(); n sc.nextInt() sc.nextInt sc if(n==0) break; n==0 n 0 break; for(i=0;i<n;++i)
		    	{
		    		ten[i]=sc.nextInt();
		    		sum=sum+ten[i];
		    	} i=0; i=0 i 0 i<n i n ++i ++i i {
		    		ten[i]=sc.nextInt();
		    		sum=sum+ten[i];
		    	} {
		    		ten[i]=sc.nextInt();
		    		sum=sum+ten[i];
		    	} ten[i]=sc.nextInt() ten[i] ten i sc.nextInt() sc.nextInt sc sum=sum+ten[i] sum sum+ten[i] sum ten[i] ten i m=(double)sum/(double)n m (double)sum/(double)n (double)sum (double)n for(i=0;i<n;++i)
		    	{
		    		x=x+(ten[i]-m)*(ten[i]-m);
		    	} i=0; i=0 i 0 i<n i n ++i ++i i {
		    		x=x+(ten[i]-m)*(ten[i]-m);
		    	} {
		    		x=x+(ten[i]-m)*(ten[i]-m);
		    	} x=x+(ten[i]-m)*(ten[i]-m) x x+(ten[i]-m)*(ten[i]-m) x (ten[i]-m)*(ten[i]-m) (ten[i]-m) ten[i] ten i m (ten[i]-m) ten[i] ten i m A=x/(double)n A x/(double)n x (double)n double a=Math.sqrt(A); a Math.sqrt(A) Math.sqrt Math A System.out.println(a) System.out.println System.out System System.out a sc.close() sc.close sc String[]args args public class Main {
	  public static void main(String[]args){
		    Scanner sc = new Scanner(System.in);
		    int ten[];
		    int i=0;
		    int sum;
		    double m=0.0;
		    double x=0.0;
		    double A=0.0;
		    ten = new int[1000];
		    while(true)
            {
		    	sum=0;
		    	m=0.0;
			    x=0.0;
			    A=0.0;
		    	int n=sc.nextInt();
                        if(n==0) break;
		    	for(i=0;i<n;++i)
		    	{
		    		ten[i]=sc.nextInt();
		    		sum=sum+ten[i];
		    	}
		    	m=(double)sum/(double)n;
		    	for(i=0;i<n;++i)
		    	{
		    		x=x+(ten[i]-m)*(ten[i]-m);
		    	}
		    	A=x/(double)n;
		    	double a=Math.sqrt(A);
		    	System.out.println(a);
            }
		    	sc.close();
		    }
} public class Main {
	  public static void main(String[]args){
		    Scanner sc = new Scanner(System.in);
		    int ten[];
		    int i=0;
		    int sum;
		    double m=0.0;
		    double x=0.0;
		    double A=0.0;
		    ten = new int[1000];
		    while(true)
            {
		    	sum=0;
		    	m=0.0;
			    x=0.0;
			    A=0.0;
		    	int n=sc.nextInt();
                        if(n==0) break;
		    	for(i=0;i<n;++i)
		    	{
		    		ten[i]=sc.nextInt();
		    		sum=sum+ten[i];
		    	}
		    	m=(double)sum/(double)n;
		    	for(i=0;i<n;++i)
		    	{
		    		x=x+(ten[i]-m)*(ten[i]-m);
		    	}
		    	A=x/(double)n;
		    	double a=Math.sqrt(A);
		    	System.out.println(a);
            }
		    	sc.close();
		    }
} Main
import java.util.Scanner;

public class Main {
	  public static void main(String[]args){
		    Scanner sc = new Scanner(System.in);
		    int ten[];
		    int i=0;
		    int sum;
		    double m=0.0;
		    double x=0.0;
		    double A=0.0;
		    ten = new int[1000];
		    while(true)
            {
		    	sum=0;
		    	m=0.0;
			    x=0.0;
			    A=0.0;
		    	int n=sc.nextInt();
                        if(n==0) break;
		    	for(i=0;i<n;++i)
		    	{
		    		ten[i]=sc.nextInt();
		    		sum=sum+ten[i];
		    	}
		    	m=(double)sum/(double)n;
		    	for(i=0;i<n;++i)
		    	{
		    		x=x+(ten[i]-m)*(ten[i]-m);
		    	}
		    	A=x/(double)n;
		    	double a=Math.sqrt(A);
		    	System.out.println(a);
            }
		    	sc.close();
		    }
}

