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]: ['57', 'j', 'n', '877', 'u', 'w', 'j', 'f', '8977', 'h', '469', '9417']
[A]: f, h, j, n, u, w


[Q]: ['k', 'c', 'i']
[A]: c, i, k


[Q]: ['k', 'p', 'w', 'w', '4713', '5755', '3601', '9141', 't', '147', '7003', '8179']
[A]:
k, p, t, w