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:
['f', 'a', 'r', '4009', 'k', 'a', 'g', '7725', 'v', 'b', '6705', 'a', '6583', '3159', 'c', 'w', 'x', 'h', '7625', 'p', 'y', '5645', 'k', 'r', 'j', '4175', 'r', '3103', '8631', '5999', 'p', 'g', 'h']
answer:
a, b, c, f, g, h, j, k, p, r, v, w, x, y


question:
['315', '9975', '3013', 's', '6131', 'e', 'e', 'u', 'a', '1729', 'g', 't', 'y', 'f', '7523', 'e', 'g', '489', 'm', 'p', 'f', 'e', '2077', 'e', 'g', 'c', 'l', '6389', 'k', 'b']
answer:
a, b, c, e, f, g, k, l, m, p, s, t, u, y


question:
['i', 'v', 'a', '4305', '4473', 'i', 'r', 'j', '8623', '3761', 'w', 'w', 'h', '7515', 'y', '1909', 'n', '1253', 'e', '2833', '2253']
answer:

a, e, h, i, j, n, r, v, w, y