Using pseudo code, create a data structure D that can store integers. The data structure should be able to store a mutli-set, i.e. an element can appear multiple times. The data structure should support the following operations in O(log n) time, where n is the number of distinct integers stored in D. add(x): Adds/inserts integer r into D. Even if r belongs to D, r should still be added. frequency(x): Number of times appears in D. search (x): Returns true if r is in D order(y): Number of elements in D that are larger than y. The element y may or may not be in D. If you are using BST and would like to balance the tree, you may simply write balance and assume that this operation will take O(log n) time. Analyze the worst-case run time of the operations