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:
['u', 'd', '4193', '5687', 'p', 'r', '7787', 't']
answer:
d, p, r, t, u


question:
['9201', 'f', '4759', 'e', 'h', '375', 'm', '5541', 'w', 'v', 'p', 'r', 'n', 'v', '4177', 'y', '8957', 'x', 'q', '6907', '1403', '5799', '7713', '1703', 'z', 'o', 'x', 's', 'n', 'i', '7981', 'f', 'd', '6099', '9605', 'j']
answer:

d, e, f, h, i, j, m, n, o, p, q, r, s, v, w, x, y, z