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:
['5761', '2289', '577', 't', '125', 'i', 'g', '9693', '747', 'd', '4829', '9587', 'f', 'k', 'w', 'v', '8607']
answer:
d, f, g, i, k, t, v, w


question:
['w', 'n', '729', '2491', 'n', 'x', '915', '1869', 'z', '8491', '9947', '561', '829', 'n', 't', 'i']
answer:
i, n, t, w, x, z


question:
['4305', '7565', '2905', 'w', '5703', '5235', '5007', '337', 'e', '629', 'k', 'z', 's', 'e', 'w', 'h', 'j', 'a', 'd', '8339', 'j', 'w', '8817', 'w', 'p', '7329', 'q', '2269', '3015', 'n', 'n', 'd', '2769', 'o', 's', '173', 'z', '7513', '8893', 'c']
answer:

a, c, d, e, h, j, k, n, o, p, q, s, w, z