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.

Ex Input:
['8815', 'w', '8629', 'y', '3891']

Ex Output:
w, y


Ex Input:
['1971', 'g', 't', 't', 'x', 'q', 'o', 'm', 'h', '9481', '1729', '5527', 'u', '3157', 's', '8795', 'z', 'g', 'i', '1649', 'p', '65', 's', 'u', '6843', 'r', 'l', 'k', 'n', 's', 'm', '7991', 'u', 'a']

Ex Output:
a, g, h, i, k, l, m, n, o, p, q, r, s, t, u, x, z


Ex Input:
['7929', 'n', 'w', '8489', '4071', 'z', '9205', 'e', '101', 't', 'o', 'g', '6487', '4973', '1759']

Ex Output:

e, g, n, o, t, w, z