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.
--------
Question: ['o', 'm', '8015', '787', '4787', '1727', 'f', 'e', 'c']

Answer: c, e, f, m, o


Question: ['x', 'i', 'r', '6011', 't', 'f', 'b', 'i', '8367', '4051', '1459', 'f', '5583', '9609', 'l', 'q', 'g', '8443', 'o', '8697', '7053', '8325', 'k', '7021', 'q', 'm', '6899', '9981', '8985', 'i', 'j', '8043', 'k', '535', '7603', '7629', 'k', '2779', 'g', '2049', 'x', 'd', '8527', 'k', 'q']

Answer: b, d, f, g, i, j, k, l, m, o, q, r, t, x


Question: ['2783', 'y', '4613', '9575', 'w', '1969', '3521', 'a', 'r', 'l', 'p', 'e', '851', 'h', 'l', 'd', '585', '3777', 'x', 'l', '9857', '6779', '3721', 'l', '5737', 'k', 'z', 'e', 'v', 'm', 'a', 'w', 'r', '7863', 'o', '9795', '8941', 'i', 'v', '1739', 'g', 'y']

Answer:
a, d, e, g, h, i, k, l, m, o, p, r, v, w, x, y, z