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:
['7777', '6223', 'k', 'k', 'd', '9743', '189', '7705', 'c', '6115', '4275']
answer:
c, d, k


question:
['r', 'j', '437', 'b', '5223', 'n', 'v', '437', 'd', '8285', 'k', 'j', 'r', 'p', 'n', 'e', 'n', 'j', 'o', '2651', 'j', '6365', 'q', 'q', '2159', 'g', '3641', '7727', 'c', '1197', 's', 't', 'n']
answer:
b, c, d, e, g, j, k, n, o, p, q, r, s, t, v


question:
['5395', 's', 't', '9421', '3761', 't', 'y', 'r', '2915', '4653', 'k', '2673', 'i', 'j', 'v', '3719', 'j', 'p', 'h', '1103', 'a', 'd', 'h']
answer:

a, d, h, i, j, k, p, r, s, t, v, y