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: ['3743', '765', '5299', '3069', '8547', '8991', '1811', 'k', '5557', '4907', '5907', 'd', 'r', 'z', '5385', '5463', 'f', '2063', 'm', '3419', 'k', '3897', '4049']

Answer: d, f, k, m, r, z


Question: ['7013', '8755', 'u', '9377', 'n', '6997', '507', '8557', '9745', 'g', '3019', '93', 'l', '1219', 'a', '393', '2573', 'q', 'b', '6101', 'e']

Answer: a, b, e, g, l, n, q, u


Question: ['3395', '699', '2009', '5911', 'v', '267', 'y', 'y', '8771', '4813', 's', 'm', 'c', '4215', '8151', '3643', '9265', '3713', 'a', '8507', '4409', 't', '6837', '9271']

Answer:
a, c, m, s, t, v, y