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.

['7799', '8163', '3389', 'x', 'k', 'm', '6085', 'f', '1131']
f, k, m, x

['887', 'p', '3819', '2727', '1407', 'b', 'n', '737', 'd', 'w', 'q', '6877']
b, d, n, p, q, w

['2943', 'g', 'y', '4547', 'd', 'c', 'o', 'q', 'w', '1413', 'w', '8261', 'i', '8213', 'f', '3595', 'x', 'o', '1949', 'a', '9089', 'k', 'x', '3295', 'y', '4563', 'r', '693', 's', '1627', '5563', 'e']

a, c, d, e, f, g, i, k, o, q, r, s, w, x, y