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


question:
['w', 'g', '1649', 'a', '2115', '6763', 'r', 't', 'l', 's', 'y', '5659', 'a', 'b']
answer:
a, b, g, l, r, s, t, w, y


question:
['193', '3589', '6101', 'a', '3953', '7383', '313', 'n', 'd', 'y', '5237', 'a', 'i', '6475', '4733', '5431', 'a', 'v', 'f', '8793', '1391', '1361']
answer:

a, d, f, i, n, v, y