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: ['9689', '9727', 't', 'd', '2103', 'c', 'n', '8553', '4559', '7815', 'u', 'l', 'c', 'e', 'u', 'n', '7207', '4875', '7699', 'h']

Answer: c, d, e, h, l, n, t, u


Question: ['u', 'd', '4193', '5687', 'p', 'r', '7787', 't']

Answer: d, p, r, t, u


Question: ['b', 'r', '2925']

Answer:
b, r