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:
['k', 'v', 'e', '6377', 'y', '3585', '4535', 'f', 'g', 'm', 'f', '8369', 'v', '7445', '4527', '9383', 'n']
answer:
e, f, g, k, m, n, v, y


question:
['d', '2359', '6571', 'c', 'n', 'u', '9513', '9321', '1689', 'b', '969', '1823', 'e', 'b', '9147', 's', '1811', 'k', '5443', '8699', '5483', 'v', 'w', 'n', '1215']
answer:
b, c, d, e, k, n, s, u, v, w


question:
['5589', '6969', 'c', '4745', '9869', '8185', 'u', 'i', 'c', 'j', 's', '3763', '243', '9415', 'x', 'm', '3091', 'y', 'm', 'j', '3413', '3787', 'j', 'g', '4679', 't', '1087', 'o', '7693', '6215', 'q', '3017', 'g', 'g', 'v', 'o', 'f', '2933', '4157']
answer:

c, f, g, i, j, m, o, q, s, t, u, v, x, y