Given the task definition and input, reply with output. 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.

['4107', 'g', 'l', '2875', 'r', 'c', 'b', 'a', '239', '3945', 'm', '5733', '8571', '8619', 'n', 'x', 'h', '4165', '6599', 'y', 'x', 'x', 'u', 'i', 'y']

a, b, c, g, h, i, l, m, n, r, u, x, y