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:
['4637', 'f', '2639', '8623', 'w', 'e', 'k', '5503', 'x', '6633', '7553', '1455', 'u', '1773', 'r', 'u', '1489', 'u', '1303', '9683', 'z', '565', '7041', 'x', 'z', '9431', 'k', 'v', 'j', 'z', '5469', '5665', '4089', '4951', '8263', '5675', '4095', '7745', 'z', '2437', 'd', 'e', 'w']
answer:
d, e, f, j, k, r, u, v, w, x, z


question:
['t', 'a', '2481', '2841', 'a', '2871', 'm', '4435', 'g', '8201', '4351', '9045', 'o']
answer:
a, g, m, o, t


question:
['2907', 'h', '2613', '7161', '4559', '3897', '6627', '3625', 'y', '5545', '2557', '7859', '629', '789', 'e']
answer:

e, h, y