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: ['2527', '9123', '8717']

Answer: -1


Question: ['e', 'z', '5199', 'x']

Answer: e, x, z


Question: ['7241', '1275', '5423', 'n', 'w', 'm', '6179', 't', 'r', 'z', 'a', '5773']

Answer:
a, m, n, r, t, w, z