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.
--------
Question: ['9117', '1153', 'f', 'b', '9979']

Answer: b, f


Question: ['1593', '8165', 'q', '6689', 'b', 'r', '373', 'g', '6505', '415', '495', 'j', 'j', 'f']

Answer: b, f, g, j, q, r


Question: ['x', '3719', '7231', '3185', 'l', '4497', 'a', 'f', '887']

Answer:
a, f, l, x