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:
['2161', '8009', '3057', 'r', '3897', 'd', 'j', '2727', 'b', '3231', 'i', '9227', '393', '5799']
answer:
b, d, i, j, r


question:
['9351', 'v', 'h', 'z', 'g', 'f', 't', 'q', 'g', 'o', '4073', 'n', '6149', '1735', '157', 'm']
answer:
f, g, h, m, n, o, q, t, v, z


question:
['5159', 'b', 'g', 'w']
answer:

b, g, w