Code
#include<bits/stdc++.h>
using namespace std;

class node {
public:
    int num;
    node* next;
    node(int val) {
        num = val;
        next = NULL;
    }
};

// Utility function to insert node at the end of the linked list
void insertNode(node* &head, int val) {
    node* newNode = new node(val);
    
    if (head == NULL) {
        head = newNode;
        return;
    }
    
    node* temp = head;
    while (temp->next != NULL) temp = temp->next;
    
    temp->next = newNode;
}

// Utility function to check presence of intersection
node* intersectionPresent(node* head1, node* head2) {
    unordered_set<node*> st;  // Set to store visited nodes from the first list
    while (head1 != NULL) {
        st.insert(head1);  // Insert nodes of the first list into the set
        head1 = head1->next;
    }
    while (head2 != NULL) {
       