import java.util.*;

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

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