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

['e', '1251', 'y', '6689', '6389', 'h', 't', '503', '5093', 'e', '923', '7051', 'm', 'u', '4501', '3289', '6887', '8341', 'o', '3671', 'n', 'w', '7749', 's', 'j', 'o', '8429', 'q', 'v', 'p', 'd', 'g', 'i', 'f']
d, e, f, g, h, i, j, m, n, o, p, q, s, t, u, v, w, y

['3851', 'q', 'u', 'y', '2287', '9397', '5505', 'j', '679', '6637', '9223', 'b', 'v', 'q', 'r', 'g', 'f', 'v', 'g', 'd', 'r', 'm']

b, d, f, g, j, m, q, r, u, v, y