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

Output: b, t, u


Input: Consider Input: ['4641', '2881', 'c', '4827']

Output: c


Input: Consider Input: ['2945', 'a', 'e', '4221']


Output: a, e