import java.util.*;

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

    int n = sc.nextInt();
    int halfN = n / 2;

    List<Integer> list = new ArrayList<>();
    for (int i = 0; i < n; i++) {
      list.add(sc.nextInt());
    }

    Collections.sort(list);

    int result = list.get(halfN) - list.get(halfN - 1);

    System.out.println(result);
  }
} import java.util.*; util.* java public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);

    int n = sc.nextInt();
    int halfN = n / 2;

    List<Integer> list = new ArrayList<>();
    for (int i = 0; i < n; i++) {
      list.add(sc.nextInt());
    }

    Collections.sort(list);

    int result = list.get(halfN) - list.get(halfN - 1);

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

    int n = sc.nextInt();
    int halfN = n / 2;

    List<Integer> list = new ArrayList<>();
    for (int i = 0; i < n; i++) {
      list.add(sc.nextInt());
    }

    Collections.sort(list);

    int result = list.get(halfN) - list.get(halfN - 1);

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

    int n = sc.nextInt();
    int halfN = n / 2;

    List<Integer> list = new ArrayList<>();
    for (int i = 0; i < n; i++) {
      list.add(sc.nextInt());
    }

    Collections.sort(list);

    int result = list.get(halfN) - list.get(halfN - 1);

    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 int halfN = n / 2; halfN n / 2 n 2 List<Integer> list = new ArrayList<>(); list new ArrayList<>() for (int i = 0; i < n; i++) {
      list.add(sc.nextInt());
    } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
      list.add(sc.nextInt());
    } {
      list.add(sc.nextInt());
    } list.add(sc.nextInt()) list.add list sc.nextInt() sc.nextInt sc Collections.sort(list) Collections.sort Collections list int result = list.get(halfN) - list.get(halfN - 1); result list.get(halfN) - list.get(halfN - 1) list.get(halfN) list.get list halfN list.get(halfN - 1) list.get list halfN - 1 halfN 1 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();
    int halfN = n / 2;

    List<Integer> list = new ArrayList<>();
    for (int i = 0; i < n; i++) {
      list.add(sc.nextInt());
    }

    Collections.sort(list);

    int result = list.get(halfN) - list.get(halfN - 1);

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

    int n = sc.nextInt();
    int halfN = n / 2;

    List<Integer> list = new ArrayList<>();
    for (int i = 0; i < n; i++) {
      list.add(sc.nextInt());
    }

    Collections.sort(list);

    int result = list.get(halfN) - list.get(halfN - 1);

    System.out.println(result);
  }
} Main
import java.util.*;

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

    int n = sc.nextInt();
    int halfN = n / 2;

    List<Integer> list = new ArrayList<>();
    for (int i = 0; i < n; i++) {
      list.add(sc.nextInt());
    }

    Collections.sort(list);

    int result = list.get(halfN) - list.get(halfN - 1);

    System.out.println(result);
  }
}
