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


[Q]: ['w', '1367', '5389', '9515']
[A]: w


[Q]: ['1209', '8289', 'i', 'c', '3613', '6761', 'g', 'h', '3397']
[A]:
c, g, h, i