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]: ['4641', '2881', 'c', '4827']
[A]: c


[Q]: ['m', '6761']
[A]: m


[Q]: ['a', 'u', 'h', '9161', 'l', 'n', 'h', '865', 'u', 's', 'r', '1955', '2287', 'r', 'd', '4547', 'x', 'h', '669', '979', 'v']
[A]:
a, d, h, l, n, r, s, u, v, x