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 Q]: ['q', 'g', 's', 'g', 'z', '987', '777']
[EX A]: g, q, s, z

[EX Q]: ['4213', '3595', '7937', 'y', '5723', 'v', 'b', '7007']
[EX A]: b, v, y

[EX Q]: ['s', '7477', 'x', '2523', '6821', '1813', '5171', '1271']
[EX A]:
s, x