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:
['k', 'r', 'f', '4369', 'z', 'z', 'l', '143', 'r', '707', '9167', 'g', '1749', 'i']
answer:
f, g, i, k, l, r, z


question:
['w', 'i', '4383', '7667', '9617', 'y', 'a', '8051', 'w', '4857', 'y', '3953', 'u', 'o', 'y', 'i', '9201', 'g', '1807', '5367', 'g', '5263', '3995', '6665', '3113', '9433', '6315', 'm', '845', 'x', 'c', 'v', 'h', '1491', 'g', '3519', 'x', 'b', '7695']
answer:
a, b, c, g, h, i, m, o, u, v, w, x, y


question:
['b', 't', 'c', '6479', '341', '8501', '3797', '8265', 'j', '1517', 'j', 'g', 'e', 'n', 'b', '6809', '7573', 'z', '6135', '4865', 'q', '247', '6301', '9661', '4453', 'l', 'k', 'm', 'n']
answer:

b, c, e, g, j, k, l, m, n, q, t, z