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: ['5159', '6407', '4021', '6655', 'c', 'k', 'w', '7191', 'l', '4321', '1609', 'm', '1991', '9261', '511', 'p', '7495', 'b', 'e', '4647', '2711', 'd', 'y', '3835', '5037', '3613', '2695', '3367', 'm', 'j', 'y', '9561', '4889', 'a', 'z', '2253', 'p', 't', 's', '8371', '2859', 's']

Answer: a, b, c, d, e, j, k, l, m, p, s, t, w, y, z


Question: ['a', 'w', 'm', 'g', 'c', '5475', '7391', 't', '1049', 'p', 'd', '1397', 'k', 'x', 'j', '2525', 'f', '741']

Answer: a, c, d, f, g, j, k, m, p, t, w, x


Question: ['7359', 'c', 't', 'u', 'l', '4353', 'z', 'a', '4741', 'p', 'm', '2559', 'j', 'g', 'b', '8375', '8779', '769', '6103', 'o', 't', 'f', 'p', '8785', 'y', '3595', 'w', '4523', '2069', 'x', 'n', 'b', '9103', '669', 'f', 'k']

Answer:
a, b, c, f, g, j, k, l, m, n, o, p, t, u, w, x, y, z