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:
['3127', '9253', '5667', '9453']
answer:
-1


question:
['6209', 'x', 'j', 'w', '7965', '4905', '6297', '4291', '7183', 'a', 'l', '5267', 'r', '5935', 'a', '7865', 'h', 'p', '6117', 'a', 'y', 'y', 't', 'v', '7271', 'e', 'e', 'z', 'i', 'l', '4731', '2059', 'm', '5703', 'k', 'f', '8125', 'e', '7569', 'r', '2287', '593']
answer:
a, e, f, h, i, j, k, l, m, p, r, t, v, w, x, y, z


question:
['9669', '7973', '3945', '2651', '3159', 's', 's', 'g', 'p', '4351', 'g', '3207', 'f']
answer:

f, g, p, s