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: ['k', 'v', 'e', '6377', 'y', '3585', '4535', 'f', 'g', 'm', 'f', '8369', 'v', '7445', '4527', '9383', 'n']

Answer: e, f, g, k, m, n, v, y


Question: ['z', 'a', 'm', 'd', '4017', '9641', '9295', '8629', '9263', 'b', '9707', 'h', '8009', '8951', '4061', '2069', '7965', '865', 'p', '6211', 'l', '2081', '5821', 'u']

Answer:
a, b, d, h, l, m, p, u, z