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