3. Design a data structure D that can store integers. The data structure should be ale to store nent can appear multiple times. The da the following operations in O(log n) time, where n is the number of distinct integers stored in D . add(x): Adds/inserts integer a into D. Even if belongs to D, z should still be added .frequencyx) Nuber of times r appears in D search(x): Returns true if 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