4. a) Starting with an empty 2-3 tree, build the tree by inserting keys 5, 28, 19, 15, 20, and 33 into it. Illustrate your steps by showing the state of the tree after each insertion operation. b) Starting with an empty red-black tree, build the tree by inserting keys 5, 28, 19, 15, 20, and 33 into it. Illustrate your steps by showing the state of the tree after each insertion operation. c) Argue that the trees in (a) and (b) are equivalent for search operations