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:
['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:
['1189', '7143', '993', '1513', '6449', '9749', '5963', '8159', 't', '3543', 'j', 'i', '4227', '1463', '6431', '4987', 'y', 'q', 'f', '321', 'm', 'r']
answer:
f, i, j, m, q, r, t, y


question:
['z', '2307', 'h', '4763', 'h', '7357', 'q', 'b', '3641', '8315', 'i', 'm', 'f', 'o', '1515', '977', 'o', '399', '6509', '2607', 'a', 'w', 'm', 's', '5889', '169', 'w', 'r', '3647', '5303', '6957', 'e', 'g', '6533', 'q', 'l', '6017', 'v', '6827', 'b', 'p']
answer:

a, b, e, f, g, h, i, l, m, o, p, q, r, s, v, w, z