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:
['l', 'u', '3901', '341', '5801']
answer:
l, u


question:
['699', 'd', '6027', 'j', 'e', 'c', 't', '9983', '5471', '2649', 't', '2631', 'r', 'h', '293', 'j', '8699', 'p', 'k', '5433']
answer:
c, d, e, h, j, k, p, r, t


question:
['9989', '6973', 'i', '5933', '3377', '2063', 'r', '4233', '4961', 'p', 'a', '8629', '2373', '8321', '6975', 'i', 't', 'd', 't', '7979', 'l', '7177', 'p', '6499', '9865', 'm', 'r', 'z', 't', '9287', 'h', 'w', '6111', 'a', '8863']
answer:

a, d, h, i, l, m, p, r, t, w, z