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:
['e', '8391', '7065', '6141', '3335', 't', 'i', 'c', '1791', '6333', 'b', 'z', '1621', 'e', 'h', 'u', 'o', 'q', '3195', '6507', '3253', 'c', '2067', '3917', '7111', 'r', 'j', 'd', '3987', '9139', 'm', '981', 'l', 'f', '2417', 'w', '9983', 'h', 'd', '6021', 'a', 'f']
answer:
a, b, c, d, e, f, h, i, j, l, m, o, q, r, t, u, w, z


question:
['1449', 'a', '6261', '303', '4651', 'n', 'u', '1595']
answer:
a, n, u


question:
['2743', '4565', '5395', '9049', 'p', 'y', '3715', '7171', '9613', '3753', 'n']
answer:

n, p, y