kth element from end ll cpp

#include <iostream>
#include <stack>

using namespace std;

class node{

protected:
    int element;
    node* link;

public:
    //constructor that accepts only element
    node(int element) {
        this->element = element;
        this->link = NULL;
    }

    //constructor that accepts both link and element
    node(int element, node* link){
        this->element = element;
        this->link = link;
    }

    //method to update the element
    void updateData(int element){
        this->element = element;
    }

    //method to update or setup link
    void updateLink(node* link){
        this->link = link;
    }

    //method to get the element from the node
    int getElement(){
        return this->element;
    }

    //method to get the next node
    node* getNextNode(){
        return this->link;
    }
};

class Linkedlist {
public:
    node *head;

    //constructor for the Linked List class
    Linkedlist() {
        head = NULL;
    }

    //returns head node
    node *getHead() {
        return this->head;
    }

    // method to add a node at the end
    void insert(int element) {
        node *tempNode = new node(element);
        node *p = head;
        if (head == NULL) {
            head = tempNode;
            return;
        }
        else {
            while (p->getNextNode() != NULL) {
                p = p->getNextNode();
            }
            p->updateLink(tempNode);
            return;
        }
    }

    //method to display all the elements of the Linked List
    void display() {
        cout << "\n";
        node *tempNode = head;
        while (tempNode != NULL) {
            if (tempNode->getNextNode() != NULL)
                cout << tempNode->getElement() << " --> ";
            else
                cout << tempNode->getElement();

            tempNode = tempNode->getNextNode();
        }
        return;
    }

    // kth element from the end
    int k_Element_End(int k){
        node* first = this->getHead();
        node* second = this->getHead();

        for(int i=0; i < k; i++){
            second = second = second->getNextNode();
        }

        while(second != NULL){
            first = first->getNextNode();
            second = second->getNextNode();
        }

        return first->getElement();
    }
};

int main() {
    cout<<"Program to check print kth element from the in a Linked List";
    Linkedlist l1;
    l1.insert(1);
    l1.insert(3);
    l1.insert(5);
    l1.insert(7);
    l1.insert(7);
    l1.insert(8);
    l1.insert(5);
    l1.insert(3);
    l1.insert(1);

    cout<<"\nLinked list is : ";
    l1.display();
    cout<<"\nThe 5th element from the end is : "<<l1.k_Element_End(5);

    return 0;
}