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:
['u', 'i', '1185', '3795', '5417', 'k', 'b', '2629', '2635', 'z']

Ex Output:
b, i, k, u, z


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

Ex Output:
a, n, u


Ex Input:
['4761', '2781', 'p', 'b', '8627', '5297']

Ex Output:

b, p