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:
['5011', 'l', '925', 'e', 'b', '3077', 'm', '4541', '781']
answer:
b, e, l, m


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


question:
['w', '3847', '4193', 'c', '5205', 'm', 'o', '8717', '2929', 'c', '1331', '4215', '5333', '5353', 'o', 'z', 'u', '3361', 'u', 't', 't', 's', '7309', '4819', 'w']
answer:

c, m, o, s, t, u, w, z