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:
['1749', 'i', 'w', 'j', '3171', '1999', '1037', '4937', '7013', '3593', '287', 'o', 'i', 'j']
answer:
i, j, o, w


question:
['7561', 'r', '3419', 'k', 's', '5997', 'u', '6635', '7003', '8491', 'i', '9835', 'c', '8827', 'h', 'a', 'j', '7675', '1995', '1223']
answer:
a, c, h, i, j, k, r, s, u


question:
['l', 'g', 'd', 'p', '8163', '6643', 'o', 'p', 'm']
answer:

d, g, l, m, o, p