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 = Integer.parseInt(sc.next());
        int[] ary = new int[n];
        for (int i = 0; i < n; i++) {
            ary[i] = Integer.parseInt(sc.next());
        }
        Arrays.sort(ary);
        int max = n/2;
        int min = n/2 - 1;
        System.out.println(ary[max] - ary[min]);

    }
} 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 = Integer.parseInt(sc.next());
        int[] ary = new int[n];
        for (int i = 0; i < n; i++) {
            ary[i] = Integer.parseInt(sc.next());
        }
        Arrays.sort(ary);
        int max = n/2;
        int min = n/2 - 1;
        System.out.println(ary[max] - ary[min]);

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

    } main {
        Scanner sc = new Scanner(System.in);
        int n = Integer.parseInt(sc.next());
        int[] ary = new int[n];
        for (int i = 0; i < n; i++) {
            ary[i] = Integer.parseInt(sc.next());
        }
        Arrays.sort(ary);
        int max = n/2;
        int min = n/2 - 1;
        System.out.println(ary[max] - ary[min]);

    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = Integer.parseInt(sc.next()); n Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int[] ary = new int[n]; ary new int[n] n for (int i = 0; i < n; i++) {
            ary[i] = Integer.parseInt(sc.next());
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            ary[i] = Integer.parseInt(sc.next());
        } {
            ary[i] = Integer.parseInt(sc.next());
        } ary[i] = Integer.parseInt(sc.next()) ary[i] ary i Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc Arrays.sort(ary) Arrays.sort Arrays ary int max = n/2; max n/2 n 2 int min = n/2 - 1; min n/2 - 1 n/2 n 2 1 System.out.println(ary[max] - ary[min]) System.out.println System.out System System.out ary[max] - ary[min] ary[max] ary max ary[min] ary min String[] args args public class Main {

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

    }
} public class Main {

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

    }
} 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 = Integer.parseInt(sc.next());
        int[] ary = new int[n];
        for (int i = 0; i < n; i++) {
            ary[i] = Integer.parseInt(sc.next());
        }
        Arrays.sort(ary);
        int max = n/2;
        int min = n/2 - 1;
        System.out.println(ary[max] - ary[min]);

    }
}