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: ['9351', 'v', 'h', 'z', 'g', 'f', 't', 'q', 'g', 'o', '4073', 'n', '6149', '1735', '157', 'm']

SOLUTION: f, g, h, m, n, o, q, t, v, z

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: ['6427', 'z', '6693']

SOLUTION:
z