import java.util.Arrays;
import java.util.Scanner;
public class Main{
@SuppressWarnings("resource")
public static void main(String[] args) {
	Scanner sc =new Scanner(System.in);
	int N=sc.nextInt();
	int[] d=new int[N];
	for(int i=0;i<N;i++) {
		d[i]=sc.nextInt();
	}
	Arrays.sort(d);
	System.out.println(d[d.length/2]-d[d.length/2-1]);
}
} import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main{
@SuppressWarnings("resource")
public static void main(String[] args) {
	Scanner sc =new Scanner(System.in);
	int N=sc.nextInt();
	int[] d=new int[N];
	for(int i=0;i<N;i++) {
		d[i]=sc.nextInt();
	}
	Arrays.sort(d);
	System.out.println(d[d.length/2]-d[d.length/2-1]);
}
} Main @SuppressWarnings("resource")
public static void main(String[] args) {
	Scanner sc =new Scanner(System.in);
	int N=sc.nextInt();
	int[] d=new int[N];
	for(int i=0;i<N;i++) {
		d[i]=sc.nextInt();
	}
	Arrays.sort(d);
	System.out.println(d[d.length/2]-d[d.length/2-1]);
} main {
	Scanner sc =new Scanner(System.in);
	int N=sc.nextInt();
	int[] d=new int[N];
	for(int i=0;i<N;i++) {
		d[i]=sc.nextInt();
	}
	Arrays.sort(d);
	System.out.println(d[d.length/2]-d[d.length/2-1]);
} Scanner sc =new Scanner(System.in); sc new Scanner(System.in) int N=sc.nextInt(); N sc.nextInt() sc.nextInt sc int[] d=new int[N]; d new int[N] N for(int i=0;i<N;i++) {
		d[i]=sc.nextInt();
	} int i=0; int i=0; i 0 i<N i N i++ i++ i {
		d[i]=sc.nextInt();
	} {
		d[i]=sc.nextInt();
	} d[i]=sc.nextInt() d[i] d i sc.nextInt() sc.nextInt sc Arrays.sort(d) Arrays.sort Arrays d System.out.println(d[d.length/2]-d[d.length/2-1]) System.out.println System.out System System.out d[d.length/2]-d[d.length/2-1] d[d.length/2] d d.length/2 d.length d d.length 2 d[d.length/2-1] d d.length/2-1 d.length/2 d.length d d.length 2 1 String[] args args public class Main{
@SuppressWarnings("resource")
public static void main(String[] args) {
	Scanner sc =new Scanner(System.in);
	int N=sc.nextInt();
	int[] d=new int[N];
	for(int i=0;i<N;i++) {
		d[i]=sc.nextInt();
	}
	Arrays.sort(d);
	System.out.println(d[d.length/2]-d[d.length/2-1]);
}
} public class Main{
@SuppressWarnings("resource")
public static void main(String[] args) {
	Scanner sc =new Scanner(System.in);
	int N=sc.nextInt();
	int[] d=new int[N];
	for(int i=0;i<N;i++) {
		d[i]=sc.nextInt();
	}
	Arrays.sort(d);
	System.out.println(d[d.length/2]-d[d.length/2-1]);
}
} Main
import java.util.Arrays;
import java.util.Scanner;
public class Main{
@SuppressWarnings("resource")
public static void main(String[] args) {
	Scanner sc =new Scanner(System.in);
	int N=sc.nextInt();
	int[] d=new int[N];
	for(int i=0;i<N;i++) {
		d[i]=sc.nextInt();
	}
	Arrays.sort(d);
	System.out.println(d[d.length/2]-d[d.length/2-1]);
}
}