Count pairs whose sum is equal to X

//Count pairs whose sum is equal to X

import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.*;

class Node {
    int data;
    Node next;

    Node(int key) {
        data = key;
        next = null;
    }
}

class count_pairs {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int t = sc.nextInt();

        while(t-- > 0) {
            int n1 = sc.nextInt();
            Integer arr1[] = new Integer[n1];

            for(int i = 0; i < n1; i++) {
                arr1[i] = sc.nextInt();
            }

            int n2 = sc.nextInt();
            Integer arr2[] = new Integer[n2];

            for(int i = 0; i < n2; i++) {
                arr2[i] = sc.nextInt();
            }

            LinkedList<Integer> head1 = new LinkedList<>(Arrays.asList(arr1));
            LinkedList<Integer> head2 = new LinkedList<>(Arrays.asList(arr2));

            int x = sc.nextInt();
            Solution gfg = new Solution();
            System.out.println(gfg.countPairs(head1, head2, x));
        }
    }
}

class Node
{
    int data;
    Node next;

    Node(int key)
    {
        data = key;
        next = null;
    }
}

class Solution {

    public static int countPairs(LinkedList<Integer> head1, LinkedList<Integer> head2, int x) {
        Set<Integer> set = new HashSet<>(head1);
        int count = 0;

        for(Integer el: head2) {
            if(set.contains(x - el)) {
                count++;
            }
        }
        
        return count;
    }
}