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:
['5971', 'x', 'c']

Ex Output:
c, x


Ex Input:
['f', '3409', 'i', '4147', '1745', '6007', 'l', 'd', 'i']

Ex Output:
d, f, i, l


Ex Input:
['b', 'a', '4755', 'e', '1899', 'u', 'p', '3041', 'h', '5825', '6771', '5681', '3249', 'b', 'p', '8573', 'f', 'x', '2761', 'k', '1845', 'n', '8759', '7469', '3413', '8293']

Ex Output:

a, b, e, f, h, k, n, p, u, x