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: ['5553', 'f', '3881', '8867', 's', 'd', 'a', '375', '7889', '3949', '2905', 'w', 'q', 'q', 'd', '4203', 'i', '2601', 'y', 'p', 'k']

Answer: a, d, f, i, k, p, q, s, w, y


Question: ['1429', '7273']

Answer: -1


Question: ['8611', '8801', '1033', '2521', 'g', 'n', '6479', '7139', 'x', 'u', 'c', '2017', '631', 'o', '6835', 'g', 'g', '7615', '9041', 'b', '9227', '2689', 'f', '8947', '3633', 'w', 'a', '1335', 'c', 'h', 'j', 'z', 'r', '3733', '9357', 'h', '6035', '4427', '981', 'p', '4609', 'p', '9755']

Answer:
a, b, c, f, g, h, j, n, o, p, r, u, w, x, z