instruction:
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.
question:
['y', 'i', '257', '3695', 's', '6717', '4817', '4117']
answer:
i, s, y


question:
['9689', '9727', 't', 'd', '2103', 'c', 'n', '8553', '4559', '7815', 'u', 'l', 'c', 'e', 'u', 'n', '7207', '4875', '7699', 'h']
answer:
c, d, e, h, l, n, t, u


question:
['c', '4881', '6893', '3729', 'j', '2385', 'q', 'v']
answer:

c, j, q, v