reverse starting 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;
    }
};

node* reverse_K_nodes(node* head, int k){
    node* current = head;
    node* next = NULL;
    node* prev = NULL;

    while(current != NULL && k--){
        next = current->getNextNode();
        current->updateLink(prev);
        prev = current;
        current = next;
    }
    head = prev;
    current = head;
    while(current->getNextNode() != NULL){
        current = current->getNextNode();
    }
    current->updateLink(next);
    return head;
}

int main() {
    cout<<"Program to reverse k starting nodes from the Linked List";
    Linkedlist l1;
    l1.insert(1);
    l1.insert(3);
    l1.insert(5);
    l1.insert(7);
    l1.insert(8);
    l1.insert(9);
    l1.insert(11);
    l1.insert(13);

    cout<<"\nLinked list is : ";
    l1.display();
    cout<<"\nReversing first 5 nodes of the linked list";
    l1.head = reverse_K_nodes(l1.getHead(), 4);
    l1.display();

    return 0;
}