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: ['8129', 'a', '4245', 'y', 'm', 'a']
Example solution: 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'.

Problem: ['o', 'm', '6211', '2067', 's', 'n', 'a', '5643', '3431', 'h', 't', 'w', '1067', '2659', '9383', '4009', '5645', '327', '3753', '9589', 'c', '469', 'w', '1773', 'e', 'y', 'g', 'b', 'g']

Solution: a, b, c, e, g, h, m, n, o, s, t, w, y