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: ['x', 'b', '1467', 'y', '2101', 'y', 'm', '2745', 'z', '429', '7523', 'e', 'f']

Answer: b, e, f, m, x, y, z


Question: ['7187', '7081', 'j', 'i', '3725', '6333', 'h', 'f', '6639', 'r', 'n', '3559', '2785']

Answer: f, h, i, j, n, r


Question: ['y', 'z', '6911', 'p', '7507', 'r', 'x', 'f', 's', 'e', 'm', 'f', '1153', 'w', '3787', '1275', '9691', '8127', 'c', '9017', '1201', '9571', 'z', '1889', 'a', 'u', 'a']

Answer:
a, c, e, f, m, p, r, s, u, w, x, y, z