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:
['p', 'p', '7899', 'u', '971', '7289', 't', '5217', 'k', 'z', 'y', 'y', '6905', '9499', '4085', 'x', '955', 'v', 'j', '9049', '7927', '1757', '193', '2181']
answer:
j, k, p, t, u, v, x, y, z


question:
['h', '1797', '8211', 'n', 'r', '7707', '2063', '4655', 'x', '5521', '8327', 'g', '7659', 'i', 'x', 'w', '9465', '4625', 'q', '5377', 'r', '225', 'r', 'i', 'e', '4163', 'g', 'g', '3537', 's']
answer:
e, g, h, i, n, q, r, s, w, x


question:
['f', 'x', '3271', 'f', 's', 'n', 'p', '7771', 'f', 'b', '333', '9633', 'z', 'p', 'x', 'q', 'j', 's', 'r', '9515', '6941', 'i', 'e', '1159', '389', '6215', '3367', 'o', '2769', '8981', 'e', '2669', 'k', '5001', '409', 'w', 't', '1857', '839', 'p', 'u', 'r', 'b', 'j']
answer:

b, e, f, i, j, k, n, o, p, q, r, s, t, u, w, x, z