Driver Code
public static void Main ( String [ ] args ) { 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 ) ) Console . WriteLine ( " Is ▁ BST " ) ; else Console . WriteLine ( " Not ▁ a ▁ BST " ) ; } }