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:
['2329', 'i']
answer:
i


question:
['m', '6443', 'd', 'o', 'p', 'q', '3765', 'k', 'm', 'y', 'j', '3531', 'y', 't', '671', 'j', '3699', 'a', 'i', '1843', 't', 'd', '1205', 'k', 'h', '1209', '2913', '1301', 'k', 'd', '1769', '7985', 's', 'p', 'f', '4583']
answer:
a, d, f, h, i, j, k, m, o, p, q, s, t, y


question:
['c', '181', '2781', 'a', '5709', 'w', '8395', 'z', 'q', 'g', '3705', '9979', 'n', '6799', 'g', 'b', '1981', 't', 'i', 'z', 'z', 'b', '3101', '6817', 'x', '1623', '8177', '301', 'f', '1019', '6821', '5355', '9615', 'z', '3121', 's', '1799', 'p', 'i', 'l', '7643', 'f']
answer:

a, b, c, f, g, i, l, n, p, q, s, t, w, x, z