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: ['9117', '1153', 'f', 'b', '9979']

Answer: b, f


Question: ['a', 'o', 'h', 'f', 'b', '8723', 'g', '3801', 'o', 'u', 'd', '2947', 'o', 'o', '7153', 'y', 'w', 'x', 't', 'i', '6903', '8485', '3411', 'z', 'i', 'e', '1671', '4051', '757', 'k']

Answer:
a, b, d, e, f, g, h, i, k, o, t, u, w, x, y, z