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:
['g', 'u', 'q', '1375', '9491', 't', 'w', 'c', 'v', 'y', '3169', '1607']
answer:
c, g, q, t, u, v, w, y


question:
['d', 'o', '7643', '9065']
answer:
d, o


question:
['465', '8167', '4617', '9073', 'i', 'g', 'j', 'x', '9491', '9935', 'x', '4639', 'p', 'k', 'z', 'f', '549', 'q', 'h', '2285', 't', '5663', '8333', '5033', 'p', 'j', '1621']
answer:

f, g, h, i, j, k, p, q, t, x, z