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: ['7591', '7521', 'm', '1429', 'x']

Answer: m, x


Question: ['t', 't', 'p', '3245', 'x', 'g', 'i', 'u', '2599', '8613', 't', 'v', 'p', '5635', 'y', '9567', '5193', '8617', 'q', 'f']

Answer: f, g, i, p, q, t, u, v, x, y


Question: ['w', '2385', 'f', 'l', 'a', 'g', '7199', '5235', 'n', '713', '8279', 'h', 't', 'y', 'e', '8705', '5669', '3879', '2561', 'k', 'u']

Answer:
a, e, f, g, h, k, l, n, t, u, w, y