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.

['6955', '721', '2763', '8121', '9109', '6341', 'p', 't', 'x', '6963', '1137', 'z', 'u', '1949', '7029', 't', '9539', 'a', 'u', '1873']
a, p, t, u, x, z

['6411', 'x', 'i', '267', 'z', 'e', '5483', '8033', '3697', 'z', '4167', 'e', 'f', '7229', 'i', 't', '2197', 'g']
e, f, g, i, t, x, z

['c', 'i', '6115', '1555', '5027', '6327', 'k', 'h', '4905', 'l', '2259', '2679', 'b', 'x', '7535', 'd', '7527', '737', '4317', '4137', 'd', 'c', 'n', '219', 'y', '4355', '5917', '935', 'k', 'p', 'l', 'u', '2889', 'q', 'm', 'd', 'y', '3247', 'i', 'h', '2457']

b, c, d, h, i, k, l, m, n, p, q, u, x, y