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:
['a', 'a', 'b']
answer:
a, b


question:
['6209', 'x', 'j', 'w', '7965', '4905', '6297', '4291', '7183', 'a', 'l', '5267', 'r', '5935', 'a', '7865', 'h', 'p', '6117', 'a', 'y', 'y', 't', 'v', '7271', 'e', 'e', 'z', 'i', 'l', '4731', '2059', 'm', '5703', 'k', 'f', '8125', 'e', '7569', 'r', '2287', '593']
answer:
a, e, f, h, i, j, k, l, m, p, r, t, v, w, x, y, z


question:
['a', 'e', '3767', 'h', '4557', 'q', '9457', 'd', 'u', '7975', 'p', 'l', 'l', '4559', '9201', 's', '721', '5809', '8163', 'f', 'b', 'k', '6499', '6215', 'p', '8051', '5633', 'y', '9187', 'p', '6275', '7117', '311', 'm', 's', '1603', '451', 'v', '7433', 'j', 'l', '1527']
answer:

a, b, d, e, f, h, j, k, l, m, p, q, s, u, v, y