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:
['w', '9437', 's', '9819', 'q', 'q', '4443', 'p', '377', '6777', 's', 'x', 'a', 'o', '9205', '9289', '7103', 'k', 'l', '9453', '9043', 'k', 'r', 'g']
answer:
a, g, k, l, o, p, q, r, s, w, x


question:
['x', 'i', 'r', '6011', 't', 'f', 'b', 'i', '8367', '4051', '1459', 'f', '5583', '9609', 'l', 'q', 'g', '8443', 'o', '8697', '7053', '8325', 'k', '7021', 'q', 'm', '6899', '9981', '8985', 'i', 'j', '8043', 'k', '535', '7603', '7629', 'k', '2779', 'g', '2049', 'x', 'd', '8527', 'k', 'q']
answer:
b, d, f, g, i, j, k, l, m, o, q, r, t, x


question:
['n', '2299', 'j', '9525', 'g', '3481', 'v', '9527', 't', 'o', '6039', 'f', '3467', '8093', '4191', '8625', '2315', '6333', 'd', 'a', '2921', '7211', '1433', '2703', '6819', '9931', '7523', 'n']
answer:

a, d, f, g, j, n, o, t, v