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.

['815', '6967', '6553', 'r', 'y', '3641', 'q', 'b', '6131', '4289', 'w', '6093', '6055', 'i', 'b', 'y', '5107', 'v', 'g', '9709', 'x', 'i']
b, g, i, q, r, v, w, x, y

['7989', '6897', 'o', 'v', '5687', '2933', 'w', '8207', 'y', 's', 'w', '3013', 'h']
h, o, s, v, w, y

['n', '5023', '1035', 'w', '4865', 'w', 'r', 'q', 'm', '3389', '8907', 'z', '3807', '2463', 'n', 'c', 'n', '7171', '9265', '787']

c, m, n, q, r, w, z