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:
['4927', 'h', 'x', '4719', 'j', 'f', '7797', 'l', 'i', 'q', 'x', 'i', 'k', '3215', 'k', '1625', 'g', 't', 'i', 'w', 'n', '6659', '8355', '831', 'h', '9723']
answer:
f, g, h, i, j, k, l, n, q, t, w, x


question:
['u', 'h', 'i', '3051', 'o', 'e', 'f', '6279', '1041', 'n', 'k', 'v', 'f', '8289', 'e', 'j', '6997', '3173', 'e', '211', 'r', '929', '419', '1335', 'r']
answer:

e, f, h, i, j, k, n, o, r, u, v