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

[EX Q]: ['6411', 'x', 'i', '267', 'z', 'e', '5483', '8033', '3697', 'z', '4167', 'e', 'f', '7229', 'i', 't', '2197', 'g']
[EX A]: e, f, g, i, t, x, z

[EX Q]: ['7479', 'r', '4461', 'v']
[EX A]:
r, v