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: ['q', 'g', 's', 'g', 'z', '987', '777']

Answer: g, q, s, z


Question: ['1945', 't', '4477', '4439', '6569', '2021', 'y', 't', '2725', '8947', '6921', '1373', '8107', 'g', 'c', 'w', 'x', 'b', '9117', 'k', '6567', '5073', '2307', 'e', 'b', '7405', 'e', 'x', '1419', 'd', 'o', 'n', 'a', '2647', 'z', '1459', 'n', '6137', 'u', 'b', 'q', '4459']

Answer: a, b, c, d, e, g, k, n, o, q, t, u, w, x, y, z


Question: ['l', '8637', '7415', '227', 'c', '4501', '9367', 'i', '4973', '4767', 'q', 'a', 'h', 'c', '8139', 'j', '1423', 'g', '8387', 'y', 'x', '5093', '2213', 'j', 'm', 'l', 'p', '8479', '5217', '3255', 'y', '9055', 'c', '7543', '7641', 'v', 't', 'w', '2549']

Answer:
a, c, g, h, i, j, l, m, p, q, t, v, w, x, y