Driver program to test above functions
int main ( ) { struct Node * root = new Node ( 3 ) ; root -> left = new Node ( 2 ) ; root -> right = new Node ( 5 ) ; root -> left -> left = new Node ( 1 ) ; root -> left -> right = new Node ( 4 ) ; if ( isBST ( root ) ) cout << " Is ▁ BST " ; else cout << " Not ▁ a ▁ BST " ; return 0 ; }