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.

['w', '9437', 's', '9819', 'q', 'q', '4443', 'p', '377', '6777', 's', 'x', 'a', 'o', '9205', '9289', '7103', 'k', 'l', '9453', '9043', 'k', 'r', 'g']
a, g, k, l, o, p, q, r, s, w, x

['2593', '1835', '5089', 'v', '9723', 'f', '9279', '4257', '2175', '655', 'q', 's', 'v', 'j', 'm', '4471', '6419', '1685', '2793', 'x', '509', 's', '4833', '2125', 'b', '6379', '1075']
b, f, j, m, q, s, v, x

['6993', 's', 'o', 'u', 'v', '8069', '829', 'u', '1347', 'k', 'n', '355', '2899', 'i', '1209']

i, k, n, o, s, u, v