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: ['4787', 'c', '1727', '9863', '8147', '3931', 'b', '1133', '3023', '7427', '7837', 'n', '7921', 'o', 'c', '3973', '1949', 'x', 'g', 'b', 'd', '8559', '8661', '4465', 'z', '369', 'q', 'e', 'y', '8629', '7665', 'i', 'r', 'n', 'z', '9115', '1393', '4899']

Answer: b, c, d, e, g, i, n, o, q, r, x, y, z


Question: ['o', 'm', '8015', '787', '4787', '1727', 'f', 'e', 'c']

Answer: c, e, f, m, o


Question: ['b', 'k', 'm', '3049', 'y', '2219', 'c', '8729', 'n', '3609', '839', 'k', '4135', '623']

Answer:
b, c, k, m, n, y