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: ['8815', 'w', '8629', 'y', '3891']

Answer: w, y


Question: ['7055', '2573', '1713', 'x', 'm']

Answer: m, x


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

Answer:
e, k, p, x