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.

Example input: ['8129', 'a', '4245', 'y', 'm', 'a']
Example output: a, m, y
Example explanation: Here, the unique alphabets in the list are 'a', 'y', and 'm', hence their sorted order is 'a, m, y'.
Q: ['1421', 'f', '6023', 's', '9699', 'l', 'c', '3943', '2311']
A:
c, f, l, s