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.

Let me give you an example: ['8129', 'a', '4245', 'y', 'm', 'a']
The answer to this example can be: a, m, y
Here is why: Here, the unique alphabets in the list are 'a', 'y', and 'm', hence their sorted order is 'a, m, y'.

OK. solve this:
['8789', 'd', 'q', '9337', 'c', 'c', 'g', 'i', '1909', 't', 'd', 't', '3955', 'd', 'l', 'o', '4199', '3031', 'y', '8467', '1691', 'u', 'n', 'n', 'h', '2369', 'q', '6337']
Answer:
c, d, g, h, i, l, n, o, q, t, u, y