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: ['2329', 'i']

Answer: i


Question: ['9483', '501', 'j', 'k', '3103']

Answer: j, k


Question: ['i', '5433', '9071', 't', 'c', 'f', 'p', '9185', 'z', 'i', 'e', '9879', '4467', 'z', '1435', '5787', '8863', 'w', '9125']

Answer:
c, e, f, i, p, t, w, z