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:
['8859', '575', 'l', 'e', '6575', '1303', '8643', '1395', '3171']
answer:
e, l


question:
['3583', 'd', '1481', 'w', 'l', '7261', '2933', 'n', '8725', 'g', '3441', 'r', '287', '7327', '5637', 'r', '5389', 'm', 'j', 'd', 'a', 'e', 'v', '7879', '1731', 'z', '43', 'q', 'p', '4315', 'p', '3651', 'o', 'l', 's', '9787', 'h', '6735']
answer:
a, d, e, g, h, j, l, m, n, o, p, q, r, s, v, w, z


question:
['u', '8499', 'u', '6183', '9921', '4497', '9921', '6951', '6231', 'v', 'l', '1739', '5983', 'm']
answer:

l, m, u, v