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:
['2819', 'k', 'u', 'a', '4575', 'a', 't', 'a', 'f', '1507', '415', 'w', 'o', 'o']

Ex Output:
a, f, k, o, t, u, w


Ex Input:
['n', '7489', 'n', 'n', '9787', '7829', 'n', '3481', 'v', 'l', '8927', 'c', 'm', 'd']

Ex Output:
c, d, l, m, n, v


Ex Input:
['9881', '3327', 'u', 'r', 'l', 's']

Ex Output:

l, r, s, u