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: ['699', 'd', '6027', 'j', 'e', 'c', 't', '9983', '5471', '2649', 't', '2631', 'r', 'h', '293', 'j', '8699', 'p', 'k', '5433']

Answer: c, d, e, h, j, k, p, r, t


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

Answer: f


Question: ['9101', 'c', 'o', 'm', '4753', 't', 'i', 'x', 'k', 'k', '7373', '2337', 'q', '4021', 'a', '4469']

Answer:
a, c, i, k, m, o, q, t, x