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:
['4925', 'i', 'q', 'k', '7615', 'r', '7217', 'o', '8097', '9151']
answer:
i, k, o, q, r


question:
['z', '8407', 'y', 'h', '1377', '3511', '1449', 'z', '3991', 'n', 'x', 't', 'h', '6389', '8049', '6091', '7787', 'p', 'l', '5815', 'k', 'e', 's', 'a', '9491', 'w', '1909', '4801', '4725', 'i']
answer:
a, e, h, i, k, l, n, p, s, t, w, x, y, z


question:
['6033', 'f', 'e', 'n', 'x', 'j', 't', '8783', '3031', 'z', '4977', 'x', '1455', 'z', 'w', '6161', '8721', '4523', 'j', '6743', 'j', 'w', '9465', '6289', 'q', 't', '3841', 'n', '1781', '6311', 'r', '7843', '9639']
answer:

e, f, j, n, q, r, t, w, x, z