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:
['1979', 'b', 't', '1101', '7953', '2451', '7539', '6833', 'u', '49']

Ex Output:
b, t, u


Ex Input:
['9013', 'e', 'm', 'p', 'k', '161', 'k']

Ex Output:
e, k, m, p


Ex Input:
['5633', '9689', '2463', 'c', 'g', 'h', '5179', '7999', '9943', '1451', '3365', '2395', 'w', 'm', 'w', '537', '6585', '8439', 't', '5689', 'j', 'u', '4887', 'l', 'w', '9947', '3935', '6117', '4201', 'a', '815', 'e', '4593', 'q', '5937', '4101', 'a', 'v', 'm', '3981', '5']

Ex Output:

a, c, e, g, h, j, l, m, q, t, u, v, w