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:
['d', 'a', '6931', 'c', 'u', 'z', '9713', 'v', 'm', 'e', 'k', 'o', '9705', 'a', '5373', 'c', '2983', '8097', 'h', '3039', 'g', 'f', 'n', 'v', '853', '8227', '7573', 'j', 'h', 'k', 'o', 'k', '8897', 'd', 'g', 'd', 'd', '4039']
answer:
a, c, d, e, f, g, h, j, k, m, n, o, u, v, z


question:
['t', 'y', 'y', 'r', '2409', 'r', 's', '5859', '5971', 'b', 'u', 'q', '6389', 'j', '4353', 'v', 't', '8813', 'z']
answer:

b, j, q, r, s, t, u, v, y, z