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.
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Question: ['w', '6291', '3939', '9569', 'u', '1635', '3359', '8335', 'n', '2799', '7359', 'k', 'm', '2817']

Answer: k, m, n, u, w


Question: ['t', 'r', '2959', '2517', 'a', '9959', '729', '511', 'y', 'r', '465', 'c', '687', 'm', 'b', 'm', '3449', '9713', 'g', '8275', '8823', 'a', 'z', 'w', '2185', '6283', '8457', '8137', '7163', '8329']

Answer: a, b, c, g, m, r, t, w, y, z


Question: ['t', '5023', 'v', '5293', 'q', 'w', 'r', 'a', '5487', '2283', 'f', '6575', 'p', '9939', 'v', 'd', '2883', 'y', '1925', '2803', 't', 'l', 'w']

Answer:
a, d, f, l, p, q, r, t, v, w, y