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.
One example is below.
Q: ['8129', 'a', '4245', 'y', 'm', 'a']
A: a, m, y
Rationale: Here, the unique alphabets in the list are 'a', 'y', and 'm', hence their sorted order is 'a, m, y'.
Q: ['4933', 'w', 'e', '5495', '4577', 'k', 'e', '9065', 'a', 's', '7789', 'g', 'l', 's', '3131', 'g', '3419', '5267', 'j']
A:
a, e, g, j, k, l, s, w