import java.util.*;
/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode FindFirstCommonNode(ListNode pHead1, ListNode pHead2) {
        ListNode cur = pHead1;
        Set<ListNode> set = new HashSet<>();
        while(cur!=null){
            set.add(cur);
            cur = cur.next;
        }
        cur = pHead2;
        ListNode target = null;
        while(cur!=null){
            if(set.contains(cur)){
                target = cur;
                break;
            }
            cur = cur.next;
        }
        return target;
    }
}