Detailed Instructions: In this task, you are given an input list A comprising of numbers and alphabets. You need to extract and sort the unique alphabets in the list. The alphabets in the input list will only be in lowercase. Return -1 if there is no alphabet in the input list.
Q: ['6997', '8729', '2719', '357', 'w', '4617', 'p', '9517', 'e', 'w', '5885', 'u', 'p', '3685', 'r', 'd']
A:
d, e, p, r, u, w