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.parallelSort(d);
		int abc=d[n/2-1];
		int agc=d[n/2];
		int count=0;
		for(int i=abc+1;i<=agc;i++) {
			count++;
		}
		System.out.println(count);
	}
} 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.parallelSort(d);
		int abc=d[n/2-1];
		int agc=d[n/2];
		int count=0;
		for(int i=abc+1;i<=agc;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];
		for(int i=0;i<n;i++) {
			d[i]=sc.nextInt();
		}
		Arrays.parallelSort(d);
		int abc=d[n/2-1];
		int agc=d[n/2];
		int count=0;
		for(int i=abc+1;i<=agc;i++) {
			count++;
		}
		System.out.println(count);
	} 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.parallelSort(d);
		int abc=d[n/2-1];
		int agc=d[n/2];
		int count=0;
		for(int i=abc+1;i<=agc;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 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.parallelSort(d) Arrays.parallelSort Arrays d int abc=d[n/2-1]; abc d[n/2-1] d n/2-1 n/2 n 2 1 int agc=d[n/2]; agc d[n/2] d n/2 n 2 int count=0; count 0 for(int i=abc+1;i<=agc;i++) {
			count++;
		} int i=abc+1; int i=abc+1; i abc+1 abc 1 i<=agc i agc i++ i++ i {
			count++;
		} {
			count++;
		} count++ count System.out.println(count) System.out.println System.out System System.out count 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.parallelSort(d);
		int abc=d[n/2-1];
		int agc=d[n/2];
		int count=0;
		for(int i=abc+1;i<=agc;i++) {
			count++;
		}
		System.out.println(count);
	}
} 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.parallelSort(d);
		int abc=d[n/2-1];
		int agc=d[n/2];
		int count=0;
		for(int i=abc+1;i<=agc;i++) {
			count++;
		}
		System.out.println(count);
	}
} 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.parallelSort(d);
		int abc=d[n/2-1];
		int agc=d[n/2];
		int count=0;
		for(int i=abc+1;i<=agc;i++) {
			count++;
		}
		System.out.println(count);
	}
}
