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

Answer: w


Question: ['w', 'n', '729', '2491', 'n', 'x', '915', '1869', 'z', '8491', '9947', '561', '829', 'n', 't', 'i']

Answer: i, n, t, w, x, z


Question: ['d', '9261', '961', 'g', 'w', '7363', 'a', '2789', '9929', '6765', 'h', '1579']

Answer:
a, d, g, h, w


