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.
--------
Question: ['7591', '7521', 'm', '1429', 'x']

Answer: m, x


Question: ['1801', 'q', '5101', '8863', '2309', 'p', '8789', '9529', '6135', '5523', 'f', '8889', '7639', 'k', '263', '5751', '5529', 'g', '1451', '4143', 'e', '6987']

Answer: e, f, g, k, p, q


Question: ['8793', '8197', '2177', '4661', '3315', 'w', '8381', 'k', 'v', '7613', 'h', '7493', '9573', '257', '5909', 'g', '4017', '2289', '9605', 'g', '2711', 'v', '6099', 'v', '2967', 'g', 'w', 'x', '5945', 'w', 'e', '5597', '1925', 'u', '3975', '7301', 'n', '9887', '343', '7813', '3665', '6467', '5811', 'x']

Answer:
e, g, h, k, n, u, v, w, x