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:
['6249', '1235']
answer:
-1


question:
['3821', '385', 'y', '8457', '6623', 'g', '5923', 'a', '7193', 'v', 'm', '8915', 'v', '5873', 'p', 't', 'w', 'y', '3617', 'h', 'w', 'j', '8047', 'u', '2271', 'v', 'a', '2181', 's', '1051', 'b', 'a', '9967', '987', 'z', '2255', '6349', '1249', '1397', 'q']
answer:
a, b, g, h, j, m, p, q, s, t, u, v, w, y, z


question:
['2485', 'x', '2505', '241', '9579', '7211', 'z', 'a', '8579', 'e', 'h', 'o', '643', 'g', '6815', 'j', 'f', 't', '9299', '5589', 'c', '2609', 'i', 'n', 'j', '3795', '8677']
answer:

a, c, e, f, g, h, i, j, n, o, t, x, z