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:
['7073', 'd', 'e']
answer:
d, e


question:
['u', '8229', '2731', '6595', '4675', 'n', 'a', '7361', '7401', '7273', 'b', '279', '5539', '7919', 'j', 'x', '9521', '8837', '7391', 'h', 'x', 'h', '7283', 't', '3769', '2317', '9131', 'h', 'y', 'c', '1625', 'm', 'e', 'a', '8437', '7543', 'p', '2451', 'k', 'r']
answer:
a, b, c, e, h, j, k, m, n, p, r, t, u, x, y


question:
['4159', 'l', 'd', 'f', '9591', 'u', '3009', '6639', 'z', '8373', 'e', '2713', '747', 'i', 'a', '3699', 'u', '1347', 'v', '6493', '4291', 'y', 'e', 'q', 'k', 't', 'd', '6731', '1219', 'n', 'g', 'z', 't', '6439', 'w', 't', '4403', '5665', 'l', '8887', 'p']
answer:

a, d, e, f, g, i, k, l, n, p, q, t, u, v, w, y, z