Write a method called countDuplicates that returns the number of duplicates in a sorted list. The list will be in sorted order, so all of the duplicates will be grouped together. For example, if a variable list stores the values [1, 1, 1, 3, 3, 6, 9, 15, 15, 23, 23, 23, 40, 40], the call of list.countDuplicates() should return 7 because there are 2 duplicates of 1, 1 duplicate of 3, 1 duplicate of 15, 2 duplicates of 23, and 1 duplicate of 40.