convert a BST into circular doubly linked list

#include<iostream>
using namespace std;

class Node{
  public:
      int data;
      Node *left,*right;
      Node(int key){
        data=key;
        left=right=NULL;
        }
  };

class LLNode{
  public:
      int data;
      LLNode *prev,*next;
      LLNode(int key){
         data=key;
         prev=NULL,next=NULL;
        }
  };

LLNode* ConvertIntoDLL(Node *root){
  if(root==NULL)
    return NULL;
  LLNode *head=new LLNode(root->data);
  head->prev=ConvertIntoDLL(root->left);
  if(head->prev!=NULL)
    (head->prev)->next=head;
  head->next=ConvertIntoDLL(root->right);
  if(head->next!=NULL)
    (head->next)->prev=head;
  return head;
  }

LLNode* ConvertIntoCDLL(Node*root){
  if(root==NULL)
     return NULL;
  LLNode* first_node=ConvertIntoDLL(root);
  LLNode* last_node=first_node;
  while(first_node->prev!=NULL)
     first_node=first_node->prev;
  while(last_node->next!=NULL)
        last_node=last_node->next;
  first_node->prev=last_node;
  last_node->next=first_node;
  return first_node;
  }

void Insert(Node **root_ref,int key){
  if(*root_ref==NULL){
    *root_ref=new Node(key);
    return;
    }
  if((*root_ref)->data<key)
    Insert(&((*root_ref)->right),key);
  else
     if((*root_ref)->data>key)
       Insert(&((*root_ref)->left),key);
  }

int main(){
 Node *root=NULL;
 Insert(&root,5);
 Insert(&root,7);
 Insert(&root,2);
 Insert(&root,8);
 LLNode *head=ConvertIntoCDLL(root);
 LLNode *node=head;
 do{
    cout<<" "<<node->data;
    node=node->next;
   }while(node!=head);
 }