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', '1349', '3393', '7507', '2469', '8531', 'w', '6845', 'k', 'q', '2401', 'f', 'g', 'l', 'n', 'n', 'e', 'q', 'y', 'v', '3077', '4167', 'b', '5517', 'b']

Answer: b, e, f, g, k, l, n, q, v, w, y


Question: ['u', '8229', '2731', '6595', '4675', 'n', 'a', '7361', '7401', '7273', 'b', '279', '5539', '7919', 'j', 'x', '9521', '8837', '7391', 'h', 'x', 'h', '7283', 't', '3769', '2317', '9131', 'h', 'y', 'c', '1625', 'm', 'e', 'a', '8437', '7543', 'p', '2451', 'k', 'r']

Answer: a, b, c, e, h, j, k, m, n, p, r, t, u, x, y


Question: ['6797', '9531', 'k', 'a', '3781', '4367', '2879', 'q', 'u', 'd', 'p', 'w']

Answer:
a, d, k, p, q, u, w