
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[] d=new int[N];
		int K;
		
		for(int i=0;i<N;i++) {
			d[i]=sc.nextInt();
		}
		
		Arrays.sort(d);
		
		if(d[(N/2)-1]==d[N/2]) {
			K=0;
		}
		else{
			K=d[N/2]-d[(N/2)-1];
		}
		
		System.out.println(K);
		
		sc.close();
	}
} 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[] d=new int[N];
		int K;
		
		for(int i=0;i<N;i++) {
			d[i]=sc.nextInt();
		}
		
		Arrays.sort(d);
		
		if(d[(N/2)-1]==d[N/2]) {
			K=0;
		}
		else{
			K=d[N/2]-d[(N/2)-1];
		}
		
		System.out.println(K);
		
		sc.close();
	}
} Main public static void main(String[] args) {
		
		Scanner sc=new Scanner(System.in);
		
		int N=sc.nextInt();
		int[] d=new int[N];
		int K;
		
		for(int i=0;i<N;i++) {
			d[i]=sc.nextInt();
		}
		
		Arrays.sort(d);
		
		if(d[(N/2)-1]==d[N/2]) {
			K=0;
		}
		else{
			K=d[N/2]-d[(N/2)-1];
		}
		
		System.out.println(K);
		
		sc.close();
	} main {
		
		Scanner sc=new Scanner(System.in);
		
		int N=sc.nextInt();
		int[] d=new int[N];
		int K;
		
		for(int i=0;i<N;i++) {
			d[i]=sc.nextInt();
		}
		
		Arrays.sort(d);
		
		if(d[(N/2)-1]==d[N/2]) {
			K=0;
		}
		else{
			K=d[N/2]-d[(N/2)-1];
		}
		
		System.out.println(K);
		
		sc.close();
	} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int N=sc.nextInt(); N sc.nextInt() sc.nextInt sc int[] d=new int[N]; d new int[N] N int K; K for(int i=0;i<N;i++) {
			d[i]=sc.nextInt();
		} int i=0; int i=0; i 0 i<N i N i++ i++ i {
			d[i]=sc.nextInt();
		} {
			d[i]=sc.nextInt();
		} d[i]=sc.nextInt() d[i] d i sc.nextInt() sc.nextInt sc Arrays.sort(d) Arrays.sort Arrays d if(d[(N/2)-1]==d[N/2]) {
			K=0;
		}
		else{
			K=d[N/2]-d[(N/2)-1];
		} d[(N/2)-1]==d[N/2] d[(N/2)-1] d (N/2)-1 (N/2) N 2 1 d[N/2] d N/2 N 2 {
			K=0;
		} K=0 K 0 {
			K=d[N/2]-d[(N/2)-1];
		} K=d[N/2]-d[(N/2)-1] K 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 System.out.println(K) System.out.println System.out System System.out K sc.close() sc.close sc String[] args args public class Main {
	public static void main(String[] args) {
		
		Scanner sc=new Scanner(System.in);
		
		int N=sc.nextInt();
		int[] d=new int[N];
		int K;
		
		for(int i=0;i<N;i++) {
			d[i]=sc.nextInt();
		}
		
		Arrays.sort(d);
		
		if(d[(N/2)-1]==d[N/2]) {
			K=0;
		}
		else{
			K=d[N/2]-d[(N/2)-1];
		}
		
		System.out.println(K);
		
		sc.close();
	}
} public class Main {
	public static void main(String[] args) {
		
		Scanner sc=new Scanner(System.in);
		
		int N=sc.nextInt();
		int[] d=new int[N];
		int K;
		
		for(int i=0;i<N;i++) {
			d[i]=sc.nextInt();
		}
		
		Arrays.sort(d);
		
		if(d[(N/2)-1]==d[N/2]) {
			K=0;
		}
		else{
			K=d[N/2]-d[(N/2)-1];
		}
		
		System.out.println(K);
		
		sc.close();
	}
} 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[] d=new int[N];
		int K;
		
		for(int i=0;i<N;i++) {
			d[i]=sc.nextInt();
		}
		
		Arrays.sort(d);
		
		if(d[(N/2)-1]==d[N/2]) {
			K=0;
		}
		else{
			K=d[N/2]-d[(N/2)-1];
		}
		
		System.out.println(K);
		
		sc.close();
	}
}
