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:
['j', 'p', '8333', '8079', '4703', '7089', '8859', 'b', 'y', 'g', '7971', '6999', '2011', 'k', 'e', '9609', '4179', '3993', 'u', '3957', '6313', '4229', 'k', '5963', 'e', 'y', 'r', 'e', 'a', '2213', 'e', 'i', 'f', '7979', 'r', 'a', 'h', 'e', 'n']
answer:
a, b, e, f, g, h, i, j, k, n, p, r, u, y


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:
['z', '3365', '2307', '3403', 'k', '3509']
answer:

k, z