import java.util.*;

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

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