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', 'm', 'n', 'u', '9159', '7931', '5401', '1383', '8195', 't', 'x', 'q', 'r', '2535', 's', 'j', 'c', '8123', '2429', '5581', 'k', 'c', 't', 'i', 'm', 'o', 't', 'q', '4819', 't', '1649', 'r', 'y', 'z', '8813', '7451', '199', 'o', 'x', 's', 's', '6747']
answer:
c, i, j, k, m, n, o, q, r, s, t, u, x, y, z


question:
['1233', '405', '8901', '7147', '8841', 's', 'v', '3131', 'p', 'd', 'y', '5873', '439']
answer:
d, p, s, v, y


question:
['2049', '9659', '2033']
answer:

-1