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:
['s', 's', '3619', '6051', 'h', '213', '3937', 'v', 'p', 'y', '8449', '9337', '5327', 'a', 'a', 'w', '3985', 'n', 'm']
answer:
a, h, m, n, p, s, v, w, y


question:
['8815', 'w', '8629', 'y', '3891']
answer:
w, y


question:
['y', 'v', '9351', 'g', 'm', '4879', 'o', 'l', 'u', '3967', '8751', 'a', 'i', 'z', '7081']
answer:

a, g, i, l, m, o, u, v, y, z