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:
['n', 'w', '6735', '3427', '6115', 'q', '7851', '3645', 'g', '6825', '6515', '4885', 'z']
answer:
g, n, q, w, z


question:
['815', '6967', '6553', 'r', 'y', '3641', 'q', 'b', '6131', '4289', 'w', '6093', '6055', 'i', 'b', 'y', '5107', 'v', 'g', '9709', 'x', 'i']
answer:
b, g, i, q, r, v, w, x, y


question:
['a', 'l', 't', 's', 'x', 'o', 'z', 'r', 'v', 'l', '7097', 'c', 'j', '365', '2505', '6229', '7113', '529', '1293', '9543', 't', 'g', 'd', '8119', 'c', '4633', 'v', '793', 'a', 'o', 'r', '6279', '1819', 'c', 'v', '4433', 'e', '6165', '4835']
answer:

a, c, d, e, g, j, l, o, r, s, t, v, x, z