instruction:
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:
['k', 'j', 'v', '5277', '8607', 'n', '1109', 'e', 'k', '6579', 'o', '2909', 'u', 't', '9685', '8443', '9257', '8071', 'y', 'b', 'h', '4767', 'a', 'j', '8455', 'b', '7733', '2553', 'e']
answer:
a, b, e, h, j, k, n, o, t, u, v, y


question:
['6769', '1057', '1021', 'n', '8231', '9173', '8123', 'a', '6053', 'q', 'y', '883', 'r', '1215', 'x', 'o', '9531']
answer:
a, n, o, q, r, x, y


question:
['6171', '6877', 'u', '2215', 'n', 'l', '5911', 'r', '3099', 'b', '2111', 'y', 'm', '5779', '7003', '6013']
answer:

b, l, m, n, r, u, y