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: ['8975', '7199']

Answer: -1


Question: ['7591', '1403']

Answer: -1


Question: ['9445', 'x', '265', '9173', 'z', 'b', '4731', '4553', '2751', '9393', '3769', '9045', 'y', 'u', '893', '6723', '9113', '1935', '8633', '6403', '6087', '7627', 'l', '1513', '643', '851', 'h', '8881', 'n', 'v', '3207', '8765', '1397', 'k', 'f', '2633']

Answer:
b, f, h, k, l, n, u, v, x, y, z