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:
['z', 'l', '1759', 'k', '8197', 'v', '931', '2587', '7219', '3455', 'e', '8135', 'm', 'n', 'm']
answer:
e, k, l, m, n, v, z


question:
['o', '1099', 'r', '8995', 'o', '2909']
answer:
o, r


question:
['9103', '6621', 'y', 'x', '5881', '9', 'c', '4331', '633', '7221', 'g', '6009', 'z']
answer:

c, g, x, y, z