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.

['6709', 't', 'n', 'k', '991', 'a', '8899', '3563', '527', 'm', '4599', '6679', 'm', 'x', 'f', 'o', '3275', 'x', '677', 'b', '3329', '3593', '5183', '5753', 'u', '6045', '2607', 'y', '9873']
a, b, f, k, m, n, o, t, u, x, y

['5553', 'f', '3881', '8867', 's', 'd', 'a', '375', '7889', '3949', '2905', 'w', 'q', 'q', 'd', '4203', 'i', '2601', 'y', 'p', 'k']
a, d, f, i, k, p, q, s, w, y

['v', 'n', 'q', '8283', 'o', 'm', 'z', '9753', 'f', '5147', 's', 'p', '6063', '3305', '1833', 'u', '2565', '9873', '2739', 'y', 'q', 'l', 'x', 'n', '8321', 'x', 't', 'w', '2565', 'b', 'm', '8821']

b, f, l, m, n, o, p, q, s, t, u, v, w, x, y, z