import java.util.Arrays;
import java.util.Scanner;

public class Main {

	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 < d.length; i++) {
			d[i] = sc.nextInt();
		}
		Arrays.sort(d);
		int f = d.length / 2 - 1;
		int s = f + 1;
		System.out.println(d[s] - d[f]);
		sc.close();
	}
} import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main {

	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 < d.length; i++) {
			d[i] = sc.nextInt();
		}
		Arrays.sort(d);
		int f = d.length / 2 - 1;
		int s = f + 1;
		System.out.println(d[s] - d[f]);
		sc.close();
	}
} Main 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 < d.length; i++) {
			d[i] = sc.nextInt();
		}
		Arrays.sort(d);
		int f = d.length / 2 - 1;
		int s = f + 1;
		System.out.println(d[s] - d[f]);
		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int[] d = new int[N];
		for (int i = 0; i < d.length; i++) {
			d[i] = sc.nextInt();
		}
		Arrays.sort(d);
		int f = d.length / 2 - 1;
		int s = f + 1;
		System.out.println(d[s] - d[f]);
		sc.close();
	} 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 < d.length; i++) {
			d[i] = sc.nextInt();
		} int i = 0; int i = 0; i 0 i < d.length i d.length d d.length 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 int f = d.length / 2 - 1; f d.length / 2 - 1 d.length / 2 d.length d d.length 2 1 int s = f + 1; s f + 1 f 1 System.out.println(d[s] - d[f]) System.out.println System.out System System.out d[s] - d[f] d[s] d s d[f] d f sc.close() sc.close sc String[] args args public class Main {

	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 < d.length; i++) {
			d[i] = sc.nextInt();
		}
		Arrays.sort(d);
		int f = d.length / 2 - 1;
		int s = f + 1;
		System.out.println(d[s] - d[f]);
		sc.close();
	}
} public class Main {

	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 < d.length; i++) {
			d[i] = sc.nextInt();
		}
		Arrays.sort(d);
		int f = d.length / 2 - 1;
		int s = f + 1;
		System.out.println(d[s] - d[f]);
		sc.close();
	}
} Main
import java.util.Arrays;
import java.util.Scanner;

public class Main {

	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 < d.length; i++) {
			d[i] = sc.nextInt();
		}
		Arrays.sort(d);
		int f = d.length / 2 - 1;
		int s = f + 1;
		System.out.println(d[s] - d[f]);
		sc.close();
	}
}
