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:
['1649', 'l', 'i', '5901', 'o', 'g', '1197', 'a', '9327', '9835', '1095', 'k', '4489', '9149', 'o', '3095', 'z', 'u', 'y', '561', '7419', 't', 'j', '8763', 'v', '339', 'y', 'w', 'v', 'v', '1867', 'd', 'r', 'w', 'h', 'j', '1531', '3841']
answer:
a, d, g, h, i, j, k, l, o, r, t, u, v, w, y, z


question:
['9555', '5983', '1853', 'c', 'z', 't', 'p', '9041', 'd', '5919', '1621', '345', 's', '2647', '4261', '8611', 'w', 'x', 'p', '9103', '2599', '5101', '9261', 'k', '7437']
answer:
c, d, k, p, s, t, w, x, z


question:
['8083', 'f', 'p', 'u', 'b', 'm', 'q', '9613', 'i', 'r', 'o', '715', 'z', 'w', 'm', '9145', 'n', 'd', '7527', '9171', 's', '9415', '4949', 'e', 'b', 'x', '7169', 'b', '2651', 'l', 'v', 'l', 'm', 's', 'u', 's', '6799']
answer:

b, d, e, f, i, l, m, n, o, p, q, r, s, u, v, w, x, z