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: ['a', '7599', 'i', '9455', '3955', '2015', 'j', '7345', 'x', 't', 'c', '1317', '9155', '6383', '7793', 'n', '5581', 'v', '3485', 'n', 'r']

Answer: a, c, i, j, n, r, t, v, x


Question: ['w', '1367', '5389', '9515']

Answer: w


Question: ['y', 'j', 'g', '1049', '4391', 'x', '4707', '9637', '8365', '2181', 'o', '6901', '2399', 'k', '2671']

Answer:
g, j, k, o, x, y