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:
['a', '7599', 'i', '9455', '3955', '2015', 'j', '7345', 'x', 't', 'c', '1317', '9155', '6383', '7793', 'n', '5581', 'v', '3485', 'n', 'r']
answer:
a, c, i, j, n, r, t, v, x


question:
['a', 'y', 'v', 'f', 'x', 'k', 'f', 'j', '6245', '6289', 'd', '6909', '8701', 'm', '3277', 'f', 'j', 'j', '9227', '8663', '5771', 'j', 'n', 'u', '7837', 's', '2539', '6363', 'g', 'a', '1009', 'v', '1483', 'x', 'i']
answer:
a, d, f, g, i, j, k, m, n, s, u, v, x, y


question:
['t', 'p', 'p', '3715', '9799', '6429', '5433', 'h', '8599', '4391', 'e', '9073', '3903', 'j', 'u', 'n', '6597']
answer:

e, h, j, n, p, t, u