How to find a modular node in a linked list

#include <iostream>
using namespace std;
struct Node{ 
  int data; 
  Node *next; 
};
class LinkedList{
    public:
    Node* head;
    LinkedList(){
      head = NULL; 
    }
    void insert(int val){
      Node* new_node = new Node;
      new_node->data = val;
      new_node->next = NULL;
      if (head == NULL)
        head = new_node;
      else{
        Node* temp = head;
        while(temp ->next !=NULL){
          temp = temp->next;
        }
        temp->next =new_node;
      }
    }
    void print(){
      Node* temp = head;
      while(temp != NULL){
        cout << temp->data << " ";
        temp = temp->next;
      }
      cout << endl;
    }
};
Node* Modular_node(Node* head,int n){
  Node* temp = head;
  Node* mod_node = NULL;
  int index=1;
  while(temp!=NULL){
    if (index%n == 0){
      mod_node = temp;
    }
    temp = temp-> next;
    index++;
  }
  return mod_node;
}
int main(){
  LinkedList list;
  list.insert(3);
  list.insert(1);
  list.insert(9);
  list.insert(6);
  list.insert(8);
  list.insert(2);
  int n=3;
  Node* mod_node = Modular_node(list.head,n);
  cout << "Linked list : ";
  list.print();
  if (mod_node!=NULL){
    cout << "The Modular Node of the linked list is : " << mod_node -> data;
  }
  else{
    cout<<"Modular Node for this linked list does not exist";
  }
  
}