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:
['4371', '9499', 'e', 'w', '9969', '8367', '2897', '1745', 'i', '7049', '9773', 'h', '9649', 'u', '4673', '8513', '8547', 'z', '1995', '7739', '2215', '171', 'c', '7527', '2479', 't', '5223', 'p', '2313', '3243', '2281', 'r', 'c']
answer:
c, e, h, i, p, r, t, u, w, z


question:
['f', '217', '449', 't', 'j', '4097', '5561', '8317', '647', 'u', 'b', '7833', 'r', '9011', 'z', '2753', '2183', 'z', 'o', 'g', '7541', 'b', '8795', '327', 'v', 'e', 't', 'l', '4909', 'k', '7681', 'r']
answer:
b, e, f, g, j, k, l, o, r, t, u, v, z


question:
['2229', 'z', '9853', '775', 'd', 's', 'd', '275', '8057', '2809', 'g', '8415', '287', 'a', 'h', '6371', 'n', 'n', '6145', 'z', 'y', '723', 'n']
answer:

a, d, g, h, n, s, y, z