find kth smallest element in BST

#include<iostream>
using namespace std;

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

//first method
void AddNode(Node* root,int arr[],int total){
   if(root==NULL)
     return;
   static int key_index=0;
   if(key_index<total){
     AddNode(root->left,arr,total);
     arr[key_index++]=root->data;
     AddNode(root->right,arr,total);
     }
   }

int FindSmallestNumber(Node* root,int k ){
  int arr[k];
  AddNode(root,arr,k);
  return arr[k-1];
  }

// second method
Node* AddNode2(Node* root,int &count,int total){
   if(root==NULL)
     return NULL;
   Node* left=AddNode2(root->left,count,total);
   if(left)
      return left;
   if(count++==total)
      return root;
   return AddNode2(root->right,count,total);
   }

Node* FindSmallestNumber2(Node* root,int k ){
  int count=1;
  return AddNode2(root,count,k);
  }

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);
 int k=2;
 Node* temp=FindSmallestNumber2(root,k);
 if(temp)
   cout<<" "<<temp->data;
 else
   cout<<" value is not correct";
 return 0;
 }