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.

['7187', '7081', 'j', 'i', '3725', '6333', 'h', 'f', '6639', 'r', 'n', '3559', '2785']
f, h, i, j, n, r

['a', '7599', 'i', '9455', '3955', '2015', 'j', '7345', 'x', 't', 'c', '1317', '9155', '6383', '7793', 'n', '5581', 'v', '3485', 'n', 'r']
a, c, i, j, n, r, t, v, x

['g', 'm', 'a', 'l', '7761', 's', '4251', '3481', 'q', 'b', 'n', '4933', '63', 'q', '9169', 't', '7137', 'p', 'c', 'x', '3205', 's', '6389', 'h', '3981', 'm', '6771', '9443', 'u']

a, b, c, g, h, l, m, n, p, q, s, t, u, x