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.

Input: Consider Input: ['s', 'u']

Output: s, u


Input: Consider Input: ['u', '4731', 'l', 'p', '1997', '601', 'n', 'l', 'p', '211', '7355', '6537', 'w', 'x', '1741', '8145', '3689', 'm', 'y', '6945']

Output: l, m, n, p, u, w, x, y


Input: Consider Input: ['8399', 'q', 'p', '8525', 'e', '4369', 'p']


Output: e, p, q