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: ['t', 'x', '1699', '8727']

Answer: t, x


Question: ['p', '2923', 'e', 'k', '5433', '605', '5079', 'k', 'p', 'x', '4845', '4099', '6795']

Answer: e, k, p, x


Question: ['2115', 'v', 'f', 'a', '663', 'v', 'j', 'f', 'n', 'p', 'w', '9923', '4621', '1159']

Answer:
a, f, j, n, p, v, w