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:
['3743', '765', '5299', '3069', '8547', '8991', '1811', 'k', '5557', '4907', '5907', 'd', 'r', 'z', '5385', '5463', 'f', '2063', 'm', '3419', 'k', '3897', '4049']

Ex Output:
d, f, k, m, r, z


Ex Input:
['7591', '1403']

Ex Output:
-1


Ex Input:
['r', '6285', '393', 's', '6933', '6343', '5021', 'p', '2497', '7833', 't', '6443', 'g', 'q', '5125', 'b', '6165', 'j', '7025', 'y', 'b', '5683', '7919', '3961', 'p', '6735', '2743', '4727', '135', '2781', '1977', 'z', 'k']

Ex Output:

b, g, j, k, p, q, r, s, t, y, z