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: ['n', 't', '2901', '9697', 'a', 'j', 'x', 'a', '4437', '2255', '2177', 's', '3173', 'j', 't', '5713', '4091', '4253', '5553', 'i', '4533', 'i', 'e', '6899', 's', '3541', '2139', '2705', 'm', 'u']

Answer: a, e, i, j, m, n, s, t, u, x


Question: ['4637', 'f', '2639', '8623', 'w', 'e', 'k', '5503', 'x', '6633', '7553', '1455', 'u', '1773', 'r', 'u', '1489', 'u', '1303', '9683', 'z', '565', '7041', 'x', 'z', '9431', 'k', 'v', 'j', 'z', '5469', '5665', '4089', '4951', '8263', '5675', '4095', '7745', 'z', '2437', 'd', 'e', 'w']

Answer: d, e, f, j, k, r, u, v, w, x, z


Question: ['3045', '4839', 'g', 'd', '8727', 'v', '7677', 'w', '6551', '6185', '637', 'k', 'g', '3379', 'q', 'y', 't', 'y', 'd', 'k', '6021', 'p', 'b', 'k']

Answer:
b, d, g, k, p, q, t, v, w, y