//function to find height of BST
int height(Node* root) {
if(root == NULL){
return -1;
}
int sum=0;
int rheight = height(root->right);
int lheight = height(root->left);
if(lheight>rheight){
sum = lheight +1;
}
if(rheight > lheight){
sum = rheight + 1;
}
return sum;
}