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:
['a', 'w', 'm', 'g', 'c', '5475', '7391', 't', '1049', 'p', 'd', '1397', 'k', 'x', 'j', '2525', 'f', '741']
answer:
a, c, d, f, g, j, k, m, p, t, w, x


question:
['3995', 'n', 'z', '8389', '7857', '3005', 'i', 'e', '1117', 'z', '8251', 'r', 't']
answer:
e, i, n, r, t, z


question:
['4843', '1805', '9727', 'j', 'm', '9129', 'o', 'y', 'j', 'b', '1869', 'w', 'g', '7839', '6449', '7603', '3331', '675', '9671', 'd', 'x', '8953', '3125', '3785', '95', '1605', 'o', '4289', '9855', 'a', 'l', '743', '9519', 'g', '4205', '8841', '5691']
answer:

a, b, d, g, j, l, m, o, w, x, y