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', 'v', 'e', '6377', 'y', '3585', '4535', 'f', 'g', 'm', 'f', '8369', 'v', '7445', '4527', '9383', 'n']
answer:
e, f, g, k, m, n, v, y


question:
['v', '2989', 'z', '7843', 'e', '9923', 'y', 'b', '7611', 'u', 'u', '6227', '3145', 'w', '6451', 'g', '3129', 'o', 'r', 'z', '8349', 'u', 'h', 'd', 'g', 'a']
answer:
a, b, d, e, g, h, o, r, u, v, w, y, z


question:
['g', '9275', '5719', 'v', '4995', 'o', '887', '4709', '1633', 'o', 'k', '5123', '9067', '7409', '307', 't', 'z', 'k', '5179', 's', '7499', 'l', 'j', '1077', 'i', 'u', 'd', 'i', 'w', 'i', '4003', '3625', '4267', 'f', '1223', 'h', 'd', '9843', '2707', '1519', 't', '4863']
answer:

d, f, g, h, i, j, k, l, o, s, t, u, v, w, z