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: ['459', '1729', 'b', 'c', '9619', '4461', '4347', '6733', 'i', '3631', 's', 'j', 'i', 'r', '5293', 'q', '7397', '4309', 'c', 'n', 'k', '197', 'q', '8139']

Answer: b, c, i, j, k, n, q, r, s


Question: ['3797', '6117', 'x']

Answer: x


Question: ['s', '3411', 'd', 'f', '119', 'c', 's', 'k', 'v', '8811', 'i', 'g', 'r', '6809', '8747', '1051', 'w', 'j']

Answer:
c, d, f, g, i, j, k, r, s, v, w