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.

[EX Q]: ['l', 'u', '3901', '341', '5801']
[EX A]: l, u

[EX Q]: ['8235', 't', '1695', '9899', '3633', 't', '1823', 'r', 'x']
[EX A]: r, t, x

[EX Q]: ['w', 'o', 'b', '7277', 'i', 'e', '4621', 'g', '9357', '2643', '5893', '4847', 'a', '2809', 'l', '8139', 'c', '4679', '4461', 'k', '5031', '5605', '7189', '6637', 's', '5559']
[EX A]:
a, b, c, e, g, i, k, l, o, s, w