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:
['f', '6817', 'f', 'd', '3835', '3051', 'u', 'l', '7679', 'b', '3931', '1441', 'q', '8675', 's', '5487', 'y', '2279', 'x', 'y', '9513', '2875', '1771', '879', '2927', '3469', 'v', 't', 'k', '9991', '2565', '7345', '973', 'w', 'i', '6105']
answer:
b, d, f, i, k, l, q, s, t, u, v, w, x, y


question:
['e', '1251', 'y', '6689', '6389', 'h', 't', '503', '5093', 'e', '923', '7051', 'm', 'u', '4501', '3289', '6887', '8341', 'o', '3671', 'n', 'w', '7749', 's', 'j', 'o', '8429', 'q', 'v', 'p', 'd', 'g', 'i', 'f']
answer:
d, e, f, g, h, i, j, m, n, o, p, q, s, t, u, v, w, y


question:
['1211', 'h', 't', 'e', '487', 'h', '5065', '9859', '689', 'q', 'c', '1117', 'm', '8333', '2313', 'm', 'p', 'f', '2829', '1627', 'w', '7067', 'y', 'n', 'q', '979', 'u', '1377', 'h', '6971', '5201', '5911', 'i', '71', 'd', '8147', 'v', '825', '2725', '4787', '9317']
answer:

c, d, e, f, h, i, m, n, p, q, t, u, v, w, y