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.
--------
Question: ['d', 'p', 'k', '9679', 'x', 'j', '7481', '1815', 't', 'w', '6513', 'j', '5079', '5219', 'p', '9545', 'a', '1931', '9973', '8125', '5169', '2791', 't', 'd', '2057', 'e', 'x', 'y', '7409', 'u']

Answer: a, d, e, j, k, p, t, u, w, x, y


Question: ['7071', 'h', '837', 'z', 'c', '2217', 'c', '6341', '6607', 'g', '3569', 'a', 'h', 't', 'b', 'f', 'g', 'f', 'l', 'b', 'x', 'o', 'r', '8949', '8071', '1507', 'v']

Answer: a, b, c, f, g, h, l, o, r, t, v, x, z


Question: ['6121', 'e', '6259', 'l', '1483', 'q', 'p', 'x', '1129', '8055', '6973', 'c', 'b', '8607', '4523', '6389', 'g', 'o', 'c', '9809', '397', '175', '4757', '2995', '8553', 'f', '6881', 'x', '7619', 'w', '9267', '6715', 'x', '5105', 'v', '9277', '1765', '1773', 'h', 'w', '1803', 'e', '2527']

Answer:
b, c, e, f, g, h, l, o, p, q, v, w, x