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: ['8347', '4217', '2245', '8489', '2737', '1245', '3319', '7017', '1527', 'x', 'n', '9033', 'k', 'm', '4605', 'r', '6805', '6471']
A:
k, m, n, r, x