TASK DEFINITION: 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.
PROBLEM: ['9689', '9727', 't', 'd', '2103', 'c', 'n', '8553', '4559', '7815', 'u', 'l', 'c', 'e', 'u', 'n', '7207', '4875', '7699', 'h']

SOLUTION: c, d, e, h, l, n, t, u

PROBLEM: ['r', '4655', 'm', 'l', '4371', 'o', '5331', '5469', 'j', 'u', '4915', 'v', 'i', 'f', 'j', '6139', 'y', '2423', '1271', '2289', '5565', '7561', '9697', 'e', 's', 'u', '9581', 'y', '6095', '5047', '625', '9047', 'd', 's', '8307', '3615', '8145']

SOLUTION: d, e, f, i, j, l, m, o, r, s, u, v, y

PROBLEM: ['s', '3061', '7137', '1965', '5017', '1981', '245', '3829', 'l', 'y', 'g', 'z', '759', '4617', '9627', 'v', 'c', '5297', 'o', 'j', 't', 'h', 'v', 'w', '2155', '1431', 'r', '3503', '3373', 'd']

SOLUTION:
c, d, g, h, j, l, o, r, s, t, v, w, y, z