Teacher: 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.
Teacher: Now, understand the problem? If you are still confused, see the following example:
['8129', 'a', '4245', 'y', 'm', 'a']
Solution: a, m, y
Reason: Here, the unique alphabets in the list are 'a', 'y', and 'm', hence their sorted order is 'a, m, y'.

Now, solve this instance: ['6785', 'g', '6697', '2301', 'k', '3681', '4811', '3005', 'u', 'u', '5315', '5343', '1223', '1775', 't', '1663', 'g', '93', '343', '7925', 'z', 'q']
Student:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
g, k, q, t, u, z