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: ['6769', '1057', '1021', 'n', '8231', '9173', '8123', 'a', '6053', 'q', 'y', '883', 'r', '1215', 'x', 'o', '9531']

Answer: a, n, o, q, r, x, y


Question: ['n', 'h', 'h', 'e', 'p', '1265', '4853', '9433', '1227', '1619', '6381', 'o', '8285', 'k', 'u', '7471', 'm', '6887', '6579', '5813', '5563', '8535', 'n', '3743', 'h', 't', '4497', '2791', 'e', 'v', '6769', '7969', 'x', 't', 'x', 'q']

Answer: e, h, k, m, n, o, p, q, t, u, v, x


Question: ['m', '6601', 'a', '1963', 'c', '9227', '2487', '7611', '517', '7113', 'g', 'o', 'j', 'v', '3031', 'h', 'h', '3885', '6981', '8629', '7071', 'e', 'p', '1429', 'o', '7263', '4605', '7649', 'g']

Answer:
a, c, e, g, h, j, m, o, p, v