second largest element in BST

#include<iostream>
using namespace std;
class Node{
  public:
      int data;
      Node *left,*right;
      Node(int key){
        data=key;
        left=right=NULL;
        }
  };

 int SecondLargest(Node *root){
  if(root==NULL)
    return INT_MAX;
  Node* sec_largest=new Node(INT_MAX);
  if(root->left!=NULL)
    sec_largest=root->left;
  Node* largest=root;
  while(largest->right!=NULL){
    sec_largest=largest;
    largest=largest->right;
    }
  return sec_largest->data;
  }

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,6);
 Insert(&root,2);
 Insert(&root,8);
 cout<<"second largest element is :"<<SecondLargest(root);
 }