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:
['1595', '2915', 'o', 't', 'c', 'h', '3969', '5407']
answer:
c, h, o, t


question:
['j', 's', 'z', 'v', '5401', 'u', '8859', 'i', 'l', 'a', 'p', 'v', 'v', 'o', '3969', '4091', 'y', '6827', '1799', '5163', 'd', 'w', '4795', '5167', 'x', 'q', '2903', '1171', '5279', '449', '7901', 'u']
answer:
a, d, i, j, l, o, p, q, s, u, v, w, x, y, z


question:
['8069', '5619', '9913', 'e']
answer:

e