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:
['w', '6291', '3939', '9569', 'u', '1635', '3359', '8335', 'n', '2799', '7359', 'k', 'm', '2817']

Ex Output:
k, m, n, u, w


Ex Input:
['8235', 't', '1695', '9899', '3633', 't', '1823', 'r', 'x']

Ex Output:
r, t, x


Ex Input:
['z', '8761', 'd', 'b', '7145', 'o', 'i', '3519', 'i', '5707', 'r', 'm', 'b', '865', '6981', '9415', 'z', '3227', '6973', '8043', '4997', '9673', '6437', '7745', 'n']

Ex Output:

b, d, i, m, n, o, r, z