A storeroom is used to organize items stored in it on N shelves. Shelves are numbered from 0 to N-1. The K-th shelf is dedicated to items of only one type, denoted by a positive integer A[K]. Recently it was decided that it is necessary to free R consecutive shelves. Shelves cannot be reordered. What is the maximum number of types of items which still can be stored in the storeroom after freeing R consecutive shelves? Write a function: int solution (vector &A, int R); that, given an array A of N integers representing types of items stored on storeroom shelves, and an integer R representing the number of consecutive shelves to be freed, returns the maximum number of different types of items that can be stored in the storeroom after freeing R consecutive shelves. Examples: 1. Given A = [2, 1, 2, 3, 2, 2] and R = 3, your function should return 2. It can be achieved, for example, by freeing shelves 2, 3 and 4 (shelves are numbered from 0). 2. Given A = [2, 3, 1, 1, 2] and R = 2, your function should return 3. All three types can still be stored by freeing the last two shelves. 3. Given A = [20, 10, 10, 10, 30, 20] and R = 3, your function should return