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: ['f', '6817', 'f', 'd', '3835', '3051', 'u', 'l', '7679', 'b', '3931', '1441', 'q', '8675', 's', '5487', 'y', '2279', 'x', 'y', '9513', '2875', '1771', '879', '2927', '3469', 'v', 't', 'k', '9991', '2565', '7345', '973', 'w', 'i', '6105']

Answer: b, d, f, i, k, l, q, s, t, u, v, w, x, y


Question: ['5011', 'l', '925', 'e', 'b', '3077', 'm', '4541', '781']

Answer: b, e, l, m


Question: ['n', '573', 'p', '7529', '7361', 'h', 'c', '9855', 'k', '4419', 'u', '3705', '6239', 'w', '6245', 'g', 'z', '5909', '8213', '9155', '9547', '7003', '7937', 'i', '2473', 'n', '4335', 'p', 'o', 'g', '5169', 'y', 'b', '5843', 'u', 'z', '3415', '9463', '1101']

Answer:
b, c, g, h, i, k, n, o, p, u, w, y, z