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:
['2995', '8179', '8131', '5655', 'j', 'q', 'l', '3193', '1823', 'y', 'n', '7645', 's', '5665', 'r']
answer:
j, l, n, q, r, s, y


question:
['m', 'z', 'd', '4667', 'v', '2881', '887', 's', '9861', 'd', '8821', '125', 't', '4493', '6749', '2983', '309', '6033', 'i', '3421', 'j', '4001']
answer:
d, i, j, m, s, t, v, z


question:
['5903', 'r', 'c', '7739', '5001', 'f', 'm', 'k', '5173', 'k', 'w', 'm', '9827', '421', 'e', 'p', 'r', 'd', 'n', 'i', 'i', 'r', 'q', 'u', 'o', 'v', 'i', '8477', '9013', 'a', '3299', '4511', '2991', '7691', '8899', '3423', 'v', 'l', '5095']
answer:

a, c, d, e, f, i, k, l, m, n, o, p, q, r, u, v, w