
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 < n ; i++) {
			d[i] = sc.nextInt();
		}
		Arrays.sort(d);
		int start;
		int end;
		if(d.length % 2 == 0) {
			start = d[d.length / 2 - 1];
			end = d[d.length / 2];
		} else {
			start = d[d.length / 2];
			end = d[d.length / 2 + 1];
		}
		System.out.println(end - start);
		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 < n ; i++) {
			d[i] = sc.nextInt();
		}
		Arrays.sort(d);
		int start;
		int end;
		if(d.length % 2 == 0) {
			start = d[d.length / 2 - 1];
			end = d[d.length / 2];
		} else {
			start = d[d.length / 2];
			end = d[d.length / 2 + 1];
		}
		System.out.println(end - start);
		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 < n ; i++) {
			d[i] = sc.nextInt();
		}
		Arrays.sort(d);
		int start;
		int end;
		if(d.length % 2 == 0) {
			start = d[d.length / 2 - 1];
			end = d[d.length / 2];
		} else {
			start = d[d.length / 2];
			end = d[d.length / 2 + 1];
		}
		System.out.println(end - start);
		sc.close();

	} 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);
		int start;
		int end;
		if(d.length % 2 == 0) {
			start = d[d.length / 2 - 1];
			end = d[d.length / 2];
		} else {
			start = d[d.length / 2];
			end = d[d.length / 2 + 1];
		}
		System.out.println(end - start);
		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 < 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 int start; start int end; end if(d.length % 2 == 0) {
			start = d[d.length / 2 - 1];
			end = d[d.length / 2];
		} else {
			start = d[d.length / 2];
			end = d[d.length / 2 + 1];
		} d.length % 2 == 0 d.length % 2 d.length d d.length 2 0 {
			start = d[d.length / 2 - 1];
			end = d[d.length / 2];
		} start = d[d.length / 2 - 1] start d[d.length / 2 - 1] d d.length / 2 - 1 d.length / 2 d.length d d.length 2 1 end = d[d.length / 2] end d[d.length / 2] d d.length / 2 d.length d d.length 2 {
			start = d[d.length / 2];
			end = d[d.length / 2 + 1];
		} start = d[d.length / 2] start d[d.length / 2] d d.length / 2 d.length d d.length 2 end = d[d.length / 2 + 1] end d[d.length / 2 + 1] d d.length / 2 + 1 d.length / 2 d.length d d.length 2 1 System.out.println(end - start) System.out.println System.out System System.out end - start end start 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 < n ; i++) {
			d[i] = sc.nextInt();
		}
		Arrays.sort(d);
		int start;
		int end;
		if(d.length % 2 == 0) {
			start = d[d.length / 2 - 1];
			end = d[d.length / 2];
		} else {
			start = d[d.length / 2];
			end = d[d.length / 2 + 1];
		}
		System.out.println(end - start);
		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 < n ; i++) {
			d[i] = sc.nextInt();
		}
		Arrays.sort(d);
		int start;
		int end;
		if(d.length % 2 == 0) {
			start = d[d.length / 2 - 1];
			end = d[d.length / 2];
		} else {
			start = d[d.length / 2];
			end = d[d.length / 2 + 1];
		}
		System.out.println(end - start);
		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 < n ; i++) {
			d[i] = sc.nextInt();
		}
		Arrays.sort(d);
		int start;
		int end;
		if(d.length % 2 == 0) {
			start = d[d.length / 2 - 1];
			end = d[d.length / 2];
		} else {
			start = d[d.length / 2];
			end = d[d.length / 2 + 1];
		}
		System.out.println(end - start);
		sc.close();

	}

}
