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:
['a', 'i', '7725', '2483', 'e', 'j', '5337', 'b', '6835', '8231', 'm', 'v', 'a', '1475', 'n', '5823', 's', 'm', '7313', '2841', '2585', '4673', 'u', '2083', 'z', 'd', 'p', '2117', 'i', '587', 'i', 'a', '2527', '7967', '6567', 'n', '6145', 'r', 'f']
answer:
a, b, d, e, f, i, j, m, n, p, r, s, u, v, z


question:
['y', 'i', '257', '3695', 's', '6717', '4817', '4117']
answer:
i, s, y


question:
['3781', '273', 'e', '2601', 'r', 'n', 'w', 'x', 'j', 'v', '7949', 's', 'v']
answer:

e, j, n, r, s, v, w, x