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: ['a', '2579', 'f', '6787', '123', '225', '6499', '4419', 'o', '1785', '7981', 'z', 'b', '2441', '2821', 'o', 'k', '2747', 's', 'u', 'q', '3901', '7629', 'k', 'm', 'q', '6577']

Answer: a, b, f, k, m, o, q, s, u, z


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: ['9589', '7215', 'n', 'm', 's', 'w', 'v', '1421', '2639', 'p', '2519', '5669', '6867', 'j', '7133', 'b', 'm', '215', '237', '725', '8557', '9397', 'c', '6319', '4655', 's', 'l', 's']

Answer:
b, c, j, l, m, n, p, s, v, w