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:
['5499', 'v', '6507', 'w', 'c', '8431', '8861', '5391', '4765', '4295', '1865', '485', '7255', '1205', 'p', 'w', 'q', '6833', '959', 'a', 'i', '2599', '7779', 'h', '9651', 'g', 'r', 'e', 'u', '4511', '1587', '5601', '8287', '5685', 'u', 'g', '2853', 'p', 'k']
answer:
a, c, e, g, h, i, k, p, q, r, u, v, w


question:
['2161', '8009', '3057', 'r', '3897', 'd', 'j', '2727', 'b', '3231', 'i', '9227', '393', '5799']
answer:
b, d, i, j, r


question:
['c', 'p', '6489', '6721', '5859', 't', '4391', '1219', 'c', '4239', '3751', '9397', '6269', 'c', '6493', 'm', 'q', '9275', '2295', 'n', 'o', '2305']
answer:

c, m, n, o, p, q, t