You will be given a definition of a task first, then some input of the task.
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.

['4931', '1643', '8845', 'z', 'e', '7307', '4945', 'g', 's', 'd', '2117', '3795', '7975', '8599', '8627', '8783', 'b', 'j', 'o', '2247', 'g', 'd', 'l', 'p', 'y', 'o', 'y', 'a', 'f', 'i', '3789', '4693', 'g', 'f', 'v', '6235', '169', '7825', 'l', 'u']
Output:
a, b, d, e, f, g, i, j, l, o, p, s, u, v, y, z