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.

['7155', 'y', '145', '7147', 'u', '8453', 'd', '3693', '6471', '5289', 'n', 'p', '8289', '2929', '199', 'e', '8377', '8937', '5315', 't', 'l', '7715', 'c', 'y', 'f', '9999', 'p', '3655', '5489', 'q', '2321', '9881', '2265', 'n', 'v', '455']
c, d, e, f, l, n, p, q, t, u, v, y

['p', 'k', 'i', '753', 'u', 'm', '3817', '1597', 'l', 'm', 'a', 'i', 'b', 's', 'c', '2561', 'x', '5363', '1173', '8657', '2033', 'b', 'p', '3093', 'k', '6535', '307', '9925', 'b', 'q', 'q']
a, b, c, i, k, l, m, p, q, s, u, x

['7993', 'm']

m