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:
['m', '7517', '9361', '9567', '8785', 'k', '5699', '3585', 'v', '1913', '1651', 'g', 'p', '2731', 'q', 'h', '467', 'r', '1091', '9801', 'a', '6645']
answer:
a, g, h, k, m, p, q, r, v


question:
['u', 'o', 'b', 'b', '5873', 'w', 'v', '4171', '7957', '3501', '2563', 'l', 'q']
answer:
b, l, o, q, u, v, w


question:
['e', 'u', 's', 'u', 'h', '6911', '3551', 'm', '7515', '5351']
answer:

e, h, m, s, u