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: ['d', 'p', 'k', '9679', 'x', 'j', '7481', '1815', 't', 'w', '6513', 'j', '5079', '5219', 'p', '9545', 'a', '1931', '9973', '8125', '5169', '2791', 't', 'd', '2057', 'e', 'x', 'y', '7409', 'u']

Answer: a, d, e, j, k, p, t, u, w, x, y


Question: ['t', 'a', '2481', '2841', 'a', '2871', 'm', '4435', 'g', '8201', '4351', '9045', 'o']

Answer: a, g, m, o, t


Question: ['r', '439', '5187', '4141', '9865', 'a', 'i', '1391', 's', 'b', 'x', 'h', 'o', '811', 'w', '4561', 'g', 'o', 'q', '3475', 'a', 'h', '3181', '3863', '6181', 'z', '5701', '9797', '5297', 'x', 'a', 'i', '9317', 'p', 'v', '739', '2495', '2783', '9467', '2627', '4083']

Answer:
a, b, g, h, i, o, p, q, r, s, v, w, x, z