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: ['2819', 'k', 'u', 'a', '4575', 'a', 't', 'a', 'f', '1507', '415', 'w', 'o', 'o']

Answer: a, f, k, o, t, u, w


Question: ['s', 'c', 'e', '2457', '9413', 'r', '9949', 's', 'z', 'e', 'a', 'o', '7207']

Answer: a, c, e, o, r, s, z


Question: ['6463', '871', '5781', '283', '9653', 'f', '9661', '3365', '2889', '5499']

Answer:
f