What is the bottleneck of binary search tree (BST)? How it is minimized by AVL Tree? Show the result of inserting the following elements 22, 45, 65, 67, 78, 89, 87, 65, 54, 43, 32, 57, 48, 39, 26, 37, 60, 40, 20 into an initially empty AVL tree. Specify the type of rotation after each insertion.