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:
['i', '1129', 'f']
answer:
f, i


question:
['7823', '2933', 'k', '4139', '5585', 'f', 'c', 'm', '2035', 'q', 'z', 'l', '1999', 'q', 'p', '7291', '2091', 'v', '423', 'e', 's', '6089', '4763', '6739']
answer:
c, e, f, k, l, m, p, q, s, v, z


question:
['5393', '6219', 'g', 't', 'j', '6613', 'g', '9327', 'd', 'e', '4051', '6047', '2193', '2835', '5315', '8385', '5669', '9105', 's', '3831', 't', 's', '6847', 'b', 'w']
answer:

b, d, e, g, j, s, t, w