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:
['4637', 'f', '2639', '8623', 'w', 'e', 'k', '5503', 'x', '6633', '7553', '1455', 'u', '1773', 'r', 'u', '1489', 'u', '1303', '9683', 'z', '565', '7041', 'x', 'z', '9431', 'k', 'v', 'j', 'z', '5469', '5665', '4089', '4951', '8263', '5675', '4095', '7745', 'z', '2437', 'd', 'e', 'w']
answer:
d, e, f, j, k, r, u, v, w, x, z


question:
['o', 'h', 'z', 'n', 'e', 'y', 't', '4371', 'm', '1059', '4853', '8529', 'l']
answer:
e, h, l, m, n, o, t, y, z


question:
['q', 'z', 'o', '2057', '4319', '6127', '5235', '8919', 'b', '9385', '4893', '1359', '7129', 'o', '1547', 'q', 'n', '4683', 'a', '3865']
answer:

a, b, n, o, q, z