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:
['f', '3409', 'i', '4147', '1745', '6007', 'l', 'd', 'i']
answer:
d, f, i, l


question:
['z', 'l', 's', 'f', 'j', 'x', '1125', 'd', '37', '5009', '9187', 'b', '8683', '8841', 'y', '9955', '1571', 'm', '347', '3679', '5797', '2133', 'g', 'u', '9817', '6347', '2067', '1927', '167', '4215', '45', 't', 'd', '6599', '4751', 'g', 'l', 'u', '7881', 's']
answer:
b, d, f, g, j, l, m, s, t, u, x, y, z


question:
['t', 'b', 'y', 'c', '1261', '6989', '1533', 'r', 's', '2929', '9857', 'u', '4449', 'x', '8873', 'j', '3513', '8587', 'n', 'x', 'y', '8257', 'k', '9745', '2695', '981', 't', '851', 'a', 'r', 'j', '7471']
answer:

a, b, c, j, k, n, r, s, t, u, x, y