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: ['6143', 'y', '5505', '9813', 'r', 'v', 'u', '8681', '2387', 'u', 'o', 'm', '9793', 'm']

Answer: m, o, r, u, v, y


Question: ['s', '2507', '3091', 'g', '7643', '2573', 'w', 'r', '1977', 'q', 'c', 'j', '1335', '9671', '7317', '567', '2041', '5777', 'w', 'm']

Answer: c, g, j, m, q, r, s, w


Question: ['g', 'd', 'k', '6779', '9869', '9467', '7499', '6397', 't', '4859', 'l', '8895', '6677', '637', '3305', 'z', '5587', 't', '6247', 'l', '9819', '7887', '8069', 't', 'x', 's', '2107', 'h', 's', '8403', '3609', '3339', '471', 'o', 'j', '4367', '3897', '2787', '7747', '8971', '6393', 'z', '8113', '3515', 't']

Answer:
d, g, h, j, k, l, o, s, t, x, z