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: ['4641', '2881', 'c', '4827']

Answer: c


Question: ['t', 'u', 'y', 'y', 'b', 'x', 'q', '3713', '2679']

Answer: b, q, t, u, x, y


Question: ['a', '9681', '7415', '6461', 'd', 'x', 'c', 'n', 'i', '9947', '9687', '8073', '8745', 'i', 'r', 'a', '3735', '955', 's', '3317', 'q', '8017', 's', 'n', 't', '2969', 'u', 'w', '3025', 'f', '4067', '8501', '7213']

Answer:
a, c, d, f, i, n, q, r, s, t, u, w, x