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:
['u', 'd', '4193', '5687', 'p', 'r', '7787', 't']
answer:
d, p, r, t, u


question:
['l', 'o', 's', '7411', '7847', '2557', '1977', '2863', '2325', '4177', '4183', '4241', '1005', '1137', '1371', 'v', 'p', 'a', '2453', 'l', '6315', 'l', '6463', 'n', '7645', '9669', '5411', '1631', '5995', 'z', '227']
answer:
a, l, n, o, p, s, v, z


question:
['1795', '2027', '6007', 'v', 'f', '3837', 's', 'z', 'x', '3665', '1071', '9503', '8183', '2543']
answer:

f, s, v, x, z