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

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

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		int n = sc.nextInt();
		int d[] = new int[n];
		for (int i = 0; i < n; i++) {
			d[i] = sc.nextInt();
		}
		Arrays.sort(d);
		int cnt = d[n / 2] - d[n / 2 - 1];
		System.out.println(cnt);
	}
}
