
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();
        if (N % 2 == 1) {
            System.out.println(0);
            return;
        }
        int[] d = new int[N];

        for (int i = 0; i < N; i++) d[i] = sc.nextInt();

        Arrays.sort(d);

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

    }
}
 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();
        if (N % 2 == 1) {
            System.out.println(0);
            return;
        }
        int[] d = new int[N];

        for (int i = 0; i < N; i++) d[i] = sc.nextInt();

        Arrays.sort(d);

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

    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        if (N % 2 == 1) {
            System.out.println(0);
            return;
        }
        int[] d = new int[N];

        for (int i = 0; i < N; i++) d[i] = sc.nextInt();

        Arrays.sort(d);

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

    } main {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        if (N % 2 == 1) {
            System.out.println(0);
            return;
        }
        int[] d = new int[N];

        for (int i = 0; i < N; i++) d[i] = sc.nextInt();

        Arrays.sort(d);

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

    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc if (N % 2 == 1) {
            System.out.println(0);
            return;
        } N % 2 == 1 N % 2 N 2 1 {
            System.out.println(0);
            return;
        } System.out.println(0) System.out.println System.out System System.out 0 return; 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] d i sc.nextInt() sc.nextInt sc Arrays.sort(d) Arrays.sort Arrays d System.out.println(d[N / 2] - d[N / 2 - 1]) System.out.println System.out System System.out 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 String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        if (N % 2 == 1) {
            System.out.println(0);
            return;
        }
        int[] d = new int[N];

        for (int i = 0; i < N; i++) d[i] = sc.nextInt();

        Arrays.sort(d);

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

    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        if (N % 2 == 1) {
            System.out.println(0);
            return;
        }
        int[] d = new int[N];

        for (int i = 0; i < N; i++) d[i] = sc.nextInt();

        Arrays.sort(d);

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

    }
} 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();
        if (N % 2 == 1) {
            System.out.println(0);
            return;
        }
        int[] d = new int[N];

        for (int i = 0; i < N; i++) d[i] = sc.nextInt();

        Arrays.sort(d);

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

    }
}

