9. Consider an array on which the following operations can be performed: addLast(e): An element 'e' is added at the end of the array. deleteEveryThird(): Removes every third element in the list i.e. removes the first, fourth, eighth, etc., elements of the array. You may assume that addLast(e) has a cost 1, and deleteEveryThird() has a cost equals to the number of elements in the list. What is the amortized cost of addLast and deleteEveryThird operations? Consider the worst sequence of operations. Justify your answer with proper explanation using accounting method