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: ['231', 'r', '5673', 'j', '589', 'z', '4659', 'a', '3763']

Answer: a, j, r, z


Question: ['e', '4863', 'd', 'o', '5177', 'x', 'i', '7067', 'g', 'i', '3981', 'w', '4035', 'e', '8265']

Answer:
d, e, g, i, o, w, x