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:
['3307', 'r', '2665', '3453', 'f', 'd', 'v', '3801', '3153', '3137', 'y', 'i', '9681', 'k', '9253', 'y', 'i', '8631', '2375', '5131', 'r', 'z', '8645', '595', 's', '6749', '2665', '709', '8203']
answer:
d, f, i, k, r, s, v, y, z


question:
['w', 'o', 'l', '1857', 's', 'q', 'j', 'e', '5945', 'g', 'l', '9563', 'e', 'u', '7633', '7977', '4943', 'y', '5621', 'f', '1653', 'c', 'l', '2843', '2125', '7731', '5257', '5667', 'b', 'b', '5765', 'a', 't', '8163', '9785', '5385']
answer:
a, b, c, e, f, g, j, l, o, q, s, t, u, w, y


question:
['4939', '6837', 'r', '6405', '2035', 'i', '3797', 'g', '3767', 'l', '8849', '3463', '3875', '727', '9397', '3725', '9323', '5435', 'b', '2069', '7195', 'u', 'j', '4783', '9881', 'b', '2519', '5137', '8141', 't']
answer:

b, g, i, j, l, r, t, u