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:
['p', 'f', 'h', '1977', '6221', 'i', 'a', 'l', '5225', '8059', 'c', 'w']
answer:
a, c, f, h, i, l, p, w


question:
['x', 'o', '8161', 's', '3653', 'v', 'c', 'e', '5353', 'h', '9145', '333', 's', '7689', '8277', 'a', 'o', 'h', 'z', 'w', '9297', 'w', '9383', '8963', 'k', 'x', 's', 'w', 'h', 'j', '5737', 'o', '2247', '3723', '2043', '4615']
answer:
a, c, e, h, j, k, o, s, v, w, x, z


question:
['6371', 't', '7127', 'k', 'w', '2227', 'c', '1619', '7753', 'r', '2649', 's', '9223', 'a', '2463', '747', '7433', 'e', 'y', '4151', 'a', 'd', 'w', '6713', 'm', 'x', '8689', 'j', '3481', '189', '8379', '8163', '5235', 'x', 'i', 'g', '7699', '5351', 'h', '5105', 's']
answer:

a, c, d, e, g, h, i, j, k, m, r, s, t, w, x, y