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:
['2393', 'c', '4413', '5529', '1487', '2499', 'i', 's', 'i', '8575', 'm', 'z', '7179', '6637', '9181', 'z', 'h', '2487', 'i', '3779', '2017', '5217', '5013']
answer:
c, h, i, m, s, z


question:
['a', '533', '67', 'z', 'z', '9283', 'o', 'a', '7045', '1521', 'm', 'h', 'q', '4173', '7497', '319', '5721', '6097', 'i', '9829', '1801', '7347', 'r', 'z', '239', '4279', 'e', 'k', 'r', 'v', '6653', '599', '8597', 'd', 'r']
answer:
a, d, e, h, i, k, m, o, q, r, v, z


question:
['1381', '5489', '6145', 'k', '6013', '8113', 'o', 'm', 'g', 'r', 'g', '9573', 'o', 'q', '8139', '2093', 'k', '6351', 'u', '6819', '929', 't', 'f', 'q', '2423', 'q', '9137', 'o', '2549', 'b', 'd', '3313', 'm', 'w', '7489', '8149', 'k', '2583', 'c', 't']
answer:

b, c, d, f, g, k, m, o, q, r, t, u, w