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:
['8451', 'x', '9965', '9303', 'm', 'f', '4205', 'y', 'n', '8521', '9995', 'z', 's', '3519', 'k', 'e', 'o', 'k', '9611', 'q', 'l', 'p', '3339', '4023', 'n', 'd', '8903', 'a', 'k', 'u', '4009', 'e', 'm', '989', '4495']
answer:
a, d, e, f, k, l, m, n, o, p, q, s, u, x, y, z


question:
['i', 's']
answer:
i, s


question:
['g', '4833', '1997', 'x', 'x', '7195', 's', 'y', 'u', 'g', 'r', 'r', 'f', '6239', '3107', '4131', 'y', 'f', 't', '485', 'o']
answer:

f, g, o, r, s, t, u, x, y