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', 'a', '6931', 'c', 'u', 'z', '9713', 'v', 'm', 'e', 'k', 'o', '9705', 'a', '5373', 'c', '2983', '8097', 'h', '3039', 'g', 'f', 'n', 'v', '853', '8227', '7573', 'j', 'h', 'k', 'o', 'k', '8897', 'd', 'g', 'd', 'd', '4039']
answer:
a, c, d, e, f, g, h, j, k, m, n, o, u, v, z


question:
['e', '1251', 'y', '6689', '6389', 'h', 't', '503', '5093', 'e', '923', '7051', 'm', 'u', '4501', '3289', '6887', '8341', 'o', '3671', 'n', 'w', '7749', 's', 'j', 'o', '8429', 'q', 'v', 'p', 'd', 'g', 'i', 'f']
answer:
d, e, f, g, h, i, j, m, n, o, p, q, s, t, u, v, w, y


question:
['3589', 'n', 'a', '3767', '5539', 'a', 'u', '8157', 'g', 'i', '3461', 'm', '2529', '4687', 's', '9373', 'i', 'l', '7891', '4277', 'c', 'm', '5453', '3533', '2067', '373', 'o', '1441', 'u']
answer:

a, c, g, i, l, m, n, o, s, u