import java.util.Scanner;
import java.util.Arrays;
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<N ; i++){
   p[i] = sc.nextInt();
   }
   int K = 0;
   Arrays.sort(p);
   K = p[(N/2)] - p[(N/2)-1];
  System.out.println(K);   
 }
} import java.util.Scanner; Scanner java.util import java.util.Arrays; Arrays 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<N ; i++){
   p[i] = sc.nextInt();
   }
   int K = 0;
   Arrays.sort(p);
   K = p[(N/2)] - p[(N/2)-1];
  System.out.println(K);   
 }
} 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<N ; i++){
   p[i] = sc.nextInt();
   }
   int K = 0;
   Arrays.sort(p);
   K = p[(N/2)] - p[(N/2)-1];
  System.out.println(K);   
 } main {
   Scanner sc = new Scanner(System.in);
   int N = sc.nextInt();
   int[] p = new int[N];
   for(int i = 0; i<N ; i++){
   p[i] = sc.nextInt();
   }
   int K = 0;
   Arrays.sort(p);
   K = p[(N/2)] - p[(N/2)-1];
  System.out.println(K);   
 } 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<N ; i++){
   p[i] = sc.nextInt();
   } int i = 0; int i = 0; i 0 i<N i N 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 K = 0; K 0 Arrays.sort(p) Arrays.sort Arrays p K = p[(N/2)] - p[(N/2)-1] K p[(N/2)] - p[(N/2)-1] p[(N/2)] p (N/2) N 2 p[(N/2)-1] p (N/2)-1 (N/2) N 2 1 System.out.println(K) System.out.println System.out System System.out K 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<N ; i++){
   p[i] = sc.nextInt();
   }
   int K = 0;
   Arrays.sort(p);
   K = p[(N/2)] - p[(N/2)-1];
  System.out.println(K);   
 }
} 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<N ; i++){
   p[i] = sc.nextInt();
   }
   int K = 0;
   Arrays.sort(p);
   K = p[(N/2)] - p[(N/2)-1];
  System.out.println(K);   
 }
} Main
import java.util.Scanner;
import java.util.Arrays;
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<N ; i++){
   p[i] = sc.nextInt();
   }
   int K = 0;
   Arrays.sort(p);
   K = p[(N/2)] - p[(N/2)-1];
  System.out.println(K);   
 }
}