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:
['u', '1805', 'l', 'l', '5449', 'r', '4471', 'a', 'u', 'c', 'q', '6463', '6717', '7025', '9359', 'q', 'h', '1989', '5497', 'h', 'd', 'c', '135', '5737', '1235', 'v', 'u', 'g', 'p', 't', '9223', '8289', '4489', 'n']
answer:
a, c, d, g, h, l, n, p, q, r, t, u, v


question:
['u', '635', '5249', '9457', 's', '9317', '9407', 'l', 'w', '9705', 'k', '429', '5489', 'e', 'd', '2457', 'o', '4665', '1675', 'l', 'y', 's', 'o', 't', '4285']
answer:
d, e, k, l, o, s, t, u, w, y


question:
['4075', '5515', '4291', '4871', 'g', 'p', '2741', 'a', 'y', '4399', '4913', '7811', 'y', 'm', 'b', 's', 'q', 'y', '749', '3551', 'f', 'a', '4061', 'a', '8615', '3089', '369', 't', '669']
answer:

a, b, f, g, m, p, q, s, t, y