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]: ['s', 'u']
[A]: s, u


[Q]: ['d', '4377', '9271', '8053', '9519']
[A]: d


[Q]: ['8341', 'l', 'r', '9705', '2293', 'n', '2575', 'f', '1999', '4199', '9543', 'y', '9669', '1365', '4889', 's', 'k', 'v', 'v', '3039', 'l', 'o', '8927', '8615', '4105', 'e', '3159']
[A]:
e, f, k, l, n, o, r, s, v, y