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:
['4925', '9943', '7935', '4387', '2449', '5797', 'i', '1517', 'w', 'e', '9525', 'y', 't', 'e', '2793', 'v', '9897', '8709', '7247', 'o', 'f', '5549', 'q']
answer:
e, f, i, o, q, t, v, w, y


question:
['c', '9125', '6049', '5201', 'v', '9311', 'q', '3305', 'l', 'q', '3387', '3647', 'x', '471', 'a', '5631', 't', '9679', '5423', '2569', 'w', 't', '6397', 'e', 'h', 'c', 'v', 'v']
answer:
a, c, e, h, l, q, t, v, w, x


question:
['o', '2081', 'q', 'x', 'v', '5879', 't', '8319', 'y', '8543', 'p', 'f', 's', 'q', 'g', 'd', 's', 'b', '7033', 'j', '9837', '7105', 'y', 'c', '4915', '1379']
answer:

b, c, d, f, g, j, o, p, q, s, t, v, x, y


