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: ['6709', 't', 'n', 'k', '991', 'a', '8899', '3563', '527', 'm', '4599', '6679', 'm', 'x', 'f', 'o', '3275', 'x', '677', 'b', '3329', '3593', '5183', '5753', 'u', '6045', '2607', 'y', '9873']

Answer: a, b, f, k, m, n, o, t, u, x, y


Question: ['h', 'l', 'i', '1507', 'h', '409', '6777', 'u', '5563', '6113', '6513', '9949', '461', 'z', 'm', '2519', 'r', '4699', 'n', 'x', '4645']

Answer: h, i, l, m, n, r, u, x, z


Question: ['1531', '2495', 't', '6581', 'g', '7095', '2493', 'd', 'r', '4079', 'r', 'e', 'e', '3699', '3491', '93', 'i', '6147', 'k', 'm']

Answer:
d, e, g, i, k, m, r, t