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:
['1449', 'a', '6261', '303', '4651', 'n', 'u', '1595']

Ex Output:
a, n, u


Ex Input:
['c', '1693', 'l', 'u', 'x', '3609', 'h', '4159']

Ex Output:
c, h, l, u, x


Ex Input:
['o', 'v', '5631', '1215', '6169', '9697', '4403', '8773', 'a', '3517', '295', 'o', 'x', 'f', '7881']

Ex Output:

a, f, o, v, x