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:
['4213', '3595', '7937', 'y', '5723', 'v', 'b', '7007']

Ex Output:
b, v, y


Ex Input:
['n', 'q', '6461', 's', '8565', '2237', '2071', '8143', '2977', '5511', 'j', 'o', '5793', 'j', 'm', 'n', '8031', 'j', '535', '5001', 's', 'y', '1737']

Ex Output:
j, m, n, o, q, s, y


Ex Input:
['1991', 'k', 'i', '1001', '2529']

Ex Output:

i, k