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.

['3887', '815', '5091', 'q', 'l', 'c', '4247', 'n', 'j', 'o', 'q', 'h', 'y', '19', 'j', 'w', 'v', 'l', 's', 'x', 'p', 'w', '8581', 'd', '4541', 'u', '6371', '4415', 'g', 'b', '939', '8941', '8735', '9671']
Output:
b, c, d, g, h, j, l, n, o, p, q, s, u, v, w, x, y