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: ['749', 'r', 'a', 's', 't', '5905', 'm', 'd', '8437', '4583']

A: a, d, m, r, s, t
****
Q: ['2409', 'q', 'w', 'e', 'x', '4737', 'w']

A: e, q, w, x
****
Q: ['h', '6469', 'b']

A:
b, h
****