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:
['c', '8389', 'j', '6113', '5843', 'f']
answer:
c, f, j

question:
['z', 'h', '2065', '6773', 'v', '151', '8957', 't', 'l', 'j', '7867', 'v', '799', '9009', '4317', 'm', '6921', 'r', '1245', '5637', 'x', '4465', 'f', 'y', '3549', 'e', 'f', 'm', 't', '6281', '4241', '3415', 'z', 'g']
answer:
e, f, g, h, j, l, m, r, t, v, x, y, z

question:
['3969', 't', '6209', 'v', 'x', '6217', '4233', 'r', '5619', 'q', '171', '8603', '7277', 'v', 'a', '1525', 'c', '3487', '4429', '2699', '8989', 'z', 'u', 'w', '6053', '2145', 'f', '3593', '9367', 'k', '1319', '1469']
answer:
a, c, f, k, q, r, t, u, v, w, x, z