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:
['f', '9203', 'w', 'f', '3751', '8095', '1319', 'f', '3017', 'r', 'y', '8221', '2715', '9959']
answer:
f, r, w, y


question:
['t', 'd', '2383', '1425', 'q', 'a', '9485', 'r', '1619', 'w', '371', 'u', 't', 'c', 'l', '2057', 'v', '2939', 'v', 'd', 'b', '5785', 's', 'l', 'q', 'j', '8577', '4913', 'm']
answer:

a, b, c, d, j, l, m, q, r, s, t, u, v, w