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

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

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