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: ['4925', 'i', 'q', 'k', '7615', 'r', '7217', 'o', '8097', '9151']

Answer: i, k, o, q, r


Question: ['u', '635', '5249', '9457', 's', '9317', '9407', 'l', 'w', '9705', 'k', '429', '5489', 'e', 'd', '2457', 'o', '4665', '1675', 'l', 'y', 's', 'o', 't', '4285']

Answer: d, e, k, l, o, s, t, u, w, y


Question: ['d', 'f', 'm', 'r', '5501', 'n', '7645']

Answer:
d, f, m, n, r