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[] p = new int[n];
        for (int i = 0; i < p.length; i++) {
            p[i] = sc.nextInt();
        }
        int a = n / 2 - 1;
        Arrays.sort(p);
        int ans = p[a + 1] - p[a];
        System.out.println(ans);
    }
} 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[] p = new int[n];
        for (int i = 0; i < p.length; i++) {
            p[i] = sc.nextInt();
        }
        int a = n / 2 - 1;
        Arrays.sort(p);
        int ans = p[a + 1] - p[a];
        System.out.println(ans);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] p = new int[n];
        for (int i = 0; i < p.length; i++) {
            p[i] = sc.nextInt();
        }
        int a = n / 2 - 1;
        Arrays.sort(p);
        int ans = p[a + 1] - p[a];
        System.out.println(ans);
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] p = new int[n];
        for (int i = 0; i < p.length; i++) {
            p[i] = sc.nextInt();
        }
        int a = n / 2 - 1;
        Arrays.sort(p);
        int ans = p[a + 1] - p[a];
        System.out.println(ans);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int[] p = new int[n]; p new int[n] n for (int i = 0; i < p.length; i++) {
            p[i] = sc.nextInt();
        } int i = 0; int i = 0; i 0 i < p.length i p.length p p.length i++ i++ i {
            p[i] = sc.nextInt();
        } {
            p[i] = sc.nextInt();
        } p[i] = sc.nextInt() p[i] p i sc.nextInt() sc.nextInt sc int a = n / 2 - 1; a n / 2 - 1 n / 2 n 2 1 Arrays.sort(p) Arrays.sort Arrays p int ans = p[a + 1] - p[a]; ans p[a + 1] - p[a] p[a + 1] p a + 1 a 1 p[a] p a System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] p = new int[n];
        for (int i = 0; i < p.length; i++) {
            p[i] = sc.nextInt();
        }
        int a = n / 2 - 1;
        Arrays.sort(p);
        int ans = p[a + 1] - p[a];
        System.out.println(ans);
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] p = new int[n];
        for (int i = 0; i < p.length; i++) {
            p[i] = sc.nextInt();
        }
        int a = n / 2 - 1;
        Arrays.sort(p);
        int ans = p[a + 1] - p[a];
        System.out.println(ans);
    }
} 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[] p = new int[n];
        for (int i = 0; i < p.length; i++) {
            p[i] = sc.nextInt();
        }
        int a = n / 2 - 1;
        Arrays.sort(p);
        int ans = p[a + 1] - p[a];
        System.out.println(ans);
    }
}