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: ['4749', '4607', '625', '6907', 't', 'b', '8479', '6505', 'r']

Answer: b, r, t


Question: ['6599', 'f', 'c', '661', 'q', 'e', '1951', 'f', 'f', 'a', 'd', '9521', '853', 'n', 'w', '6451', '5549', 'k', 't', 'l', 'z', 'm', 'k', '567']

Answer: a, c, d, e, f, k, l, m, n, q, t, w, z


Question: ['e', 'p', '6729', '5851', '1473', '8437', 'i', '2289', '4065', '1011', 'w', 'i', '2137', '7423', 'p']

Answer:
e, i, p, w