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:
['6463', '871', '5781', '283', '9653', 'f', '9661', '3365', '2889', '5499']
answer:
f


question:
['9627', '9879', '5421', '4755', '1533', '6727', 't', '7641', 'd', '3929', 'h', '3989', '8441', 'k', 'p', '2653', 'm', 'b', 'i', '3431', '4907', '5687', 'g', 'h', '9185', '5051', 'k', '7135', '709']
answer:
b, d, g, h, i, k, m, p, t


question:
['4351', 'x', 'k', 'e', '4143', '6621', 'v', '1709', 'v', 'y', 'q', '7461', 'o', 'w', 'o', '3949', 'd', '2507', 'a', 'v', 'h', 's', '333', 'o', 'v', '4471', '5149', 'v', '2191']
answer:

a, d, e, h, k, o, q, s, v, w, x, y