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:
['d', 'r', '7769', '2159', 's', '3269', '5527', 'l', 'z', 'e', '5165', 'x', 'x', '8273', 'g', 'm', '7609', '4015', '6403', '3753', 'y', 'h', 'l', 'i', '389', 'm', 'u', '6845', 'r', 'c', '7571', '3355', '9755', 'n', '4625', 'p', '5645', '1703', '4439', 't', '8431']
answer:
c, d, e, g, h, i, l, m, n, p, r, s, t, u, x, y, z


question:
['9025', '3259', '4863', 'u', '6443', '9931', '627', 'x']
answer:
u, x


question:
['x', 'e', 'r', 'j', '6457', 'c', '9935', 'z', '4973', '9725', 'd', '1027', 'f', 'p', 'z', 'i', '6197', '1933', '5459', '5311', '629', 'i', 'z', 'o', '3839', '6123', '165']
answer:

c, d, e, f, i, j, o, p, r, x, z