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();
        Integer[] d = new Integer[n];
        for (int i = 0; i < n; i++) {
            d[i] = sc.nextInt();
        }

        Arrays.sort(d);
        int start = d[d.length / 2 - 1];
        int end = d[d.length / 2];
        int result = 0;
        if (start != end) {
            result = end - start;
        }

        System.out.println(result);
    }
} 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();
        Integer[] d = new Integer[n];
        for (int i = 0; i < n; i++) {
            d[i] = sc.nextInt();
        }

        Arrays.sort(d);
        int start = d[d.length / 2 - 1];
        int end = d[d.length / 2];
        int result = 0;
        if (start != end) {
            result = end - start;
        }

        System.out.println(result);
    }
} Main public static void main(String args[]) {

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Integer[] d = new Integer[n];
        for (int i = 0; i < n; i++) {
            d[i] = sc.nextInt();
        }

        Arrays.sort(d);
        int start = d[d.length / 2 - 1];
        int end = d[d.length / 2];
        int result = 0;
        if (start != end) {
            result = end - start;
        }

        System.out.println(result);
    } main {

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Integer[] d = new Integer[n];
        for (int i = 0; i < n; i++) {
            d[i] = sc.nextInt();
        }

        Arrays.sort(d);
        int start = d[d.length / 2 - 1];
        int end = d[d.length / 2];
        int result = 0;
        if (start != end) {
            result = end - start;
        }

        System.out.println(result);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc Integer[] d = new Integer[n]; d new Integer[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 start = d[d.length / 2 - 1]; start d[d.length / 2 - 1] d d.length / 2 - 1 d.length / 2 d.length d d.length 2 1 int end = d[d.length / 2]; end d[d.length / 2] d d.length / 2 d.length d d.length 2 int result = 0; result 0 if (start != end) {
            result = end - start;
        } start != end start end {
            result = end - start;
        } result = end - start result end - start end start System.out.println(result) System.out.println System.out System System.out result String args[] args public class Main {

    public static void main(String args[]) {

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Integer[] d = new Integer[n];
        for (int i = 0; i < n; i++) {
            d[i] = sc.nextInt();
        }

        Arrays.sort(d);
        int start = d[d.length / 2 - 1];
        int end = d[d.length / 2];
        int result = 0;
        if (start != end) {
            result = end - start;
        }

        System.out.println(result);
    }
} public class Main {

    public static void main(String args[]) {

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Integer[] d = new Integer[n];
        for (int i = 0; i < n; i++) {
            d[i] = sc.nextInt();
        }

        Arrays.sort(d);
        int start = d[d.length / 2 - 1];
        int end = d[d.length / 2];
        int result = 0;
        if (start != end) {
            result = end - start;
        }

        System.out.println(result);
    }
} 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();
        Integer[] d = new Integer[n];
        for (int i = 0; i < n; i++) {
            d[i] = sc.nextInt();
        }

        Arrays.sort(d);
        int start = d[d.length / 2 - 1];
        int end = d[d.length / 2];
        int result = 0;
        if (start != end) {
            result = end - start;
        }

        System.out.println(result);
    }
}
