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

public class Main {

    private static final int MOD = 1_000_000_007;

    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 center = N / 2;

        System.out.println(d[center] - d[center - 1]);
    }
} import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main {

    private static final int MOD = 1_000_000_007;

    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 center = N / 2;

        System.out.println(d[center] - d[center - 1]);
    }
} Main private static final int MOD = 1_000_000_007; MOD 1_000_000_007 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 center = N / 2;

        System.out.println(d[center] - d[center - 1]);
    } 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 center = N / 2;

        System.out.println(d[center] - d[center - 1]);
    } 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 center = N / 2; center N / 2 N 2 System.out.println(d[center] - d[center - 1]) System.out.println System.out System System.out d[center] - d[center - 1] d[center] d center d[center - 1] d center - 1 center 1 String[] args args public class Main {

    private static final int MOD = 1_000_000_007;

    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 center = N / 2;

        System.out.println(d[center] - d[center - 1]);
    }
} public class Main {

    private static final int MOD = 1_000_000_007;

    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 center = N / 2;

        System.out.println(d[center] - d[center - 1]);
    }
} Main
import java.util.Arrays;
import java.util.Scanner;

public class Main {

    private static final int MOD = 1_000_000_007;

    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 center = N / 2;

        System.out.println(d[center] - d[center - 1]);
    }
}
