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]: ['5971', 'x', 'c']
[A]: c, x


[Q]: ['4009', 'y', '9077', 'p', 'q', '6711', '6443', '5491']
[A]: p, q, y


[Q]: ['a', '2671', '8269', '7411', '9941', '8301', 'x', 'q', 'o', '6881', '1259', '8993', 'u', '7433', 'n', 'p', '7039', 'q', '5247', '6341', '3981', '7803', '8053', 'x', 'u']
[A]:
a, n, o, p, q, u, x