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.

['2799', '7519', '345', 'e', 'l', '9369', '4703', '4111']
e, l

['w', 'g', '1649', 'a', '2115', '6763', 'r', 't', 'l', 's', 'y', '5659', 'a', 'b']
a, b, g, l, r, s, t, w, y

['4543', '481', '919', 'n', 'a', '7711', '3047', '8031', 'x', '1429', 'p', '7033', '2123', 'x', 'w', 'f', '5247', '227', 'm', 'h', 'z', 'r', '2127', 'g', '7649', 't', 'x', '4237', '3885']

a, f, g, h, m, n, p, r, t, w, x, z