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:
['y', 'p', 'q', '2157', 'b', 'w', '8875', 'k', 'i', 'd', '9743', '4941', 'b', 'p', '9941', '495', 'h', 'i', '839', 'c', 'h', 'f', 'b', 'a', 'k', 'z', '7549', '4149', 'h', 'j', '1947', 't', 'f', 'c', '1243']
answer:
a, b, c, d, f, h, i, j, k, p, q, t, w, y, z


question:
['z', '3219', '6399', '2357', '7597', '357', 'k', 'k', 'u', 'd', '6115', 'w', '2921', '8809']
answer:
d, k, u, w, z


question:
['1519', 't', 'h', '8581', '5389', 'u', 'u', 'k', '8337', '3681', 'z', '807', '6321', '7547', '1095', '8847']
answer:

h, k, t, u, z