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:
['4371', '9499', 'e', 'w', '9969', '8367', '2897', '1745', 'i', '7049', '9773', 'h', '9649', 'u', '4673', '8513', '8547', 'z', '1995', '7739', '2215', '171', 'c', '7527', '2479', 't', '5223', 'p', '2313', '3243', '2281', 'r', 'c']
answer:
c, e, h, i, p, r, t, u, w, z


question:
['231', 'r', '5673', 'j', '589', 'z', '4659', 'a', '3763']
answer:
a, j, r, z


question:
['y', 'x', '7927', 'z', '5461', '4171', '6801', 'm', 'z', '7177', 'b', 'z', '2679', '6697', '5497', 'o', '6103', '9151', 'a', 'o', '9079', '5869', '5005', 'z', '6207', 'n', 't', '4391', 'g']
answer:

a, b, g, m, n, o, t, x, y, z