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: ['2819', 'k', 'u', 'a', '4575', 'a', 't', 'a', 'f', '1507', '415', 'w', 'o', 'o']

SOLUTION: a, f, k, o, t, u, w

PROBLEM: ['2453', 'r', 'd', '8499', 't', 's', 'h', 'a', 'm', '9271', 'g', '2599', '6209', 'o', 'i', '4069', 't', '6793', '7679', '6643', '7359', 'm', 'f', 'w', '775', '3347', '6161', '9745', 'i']

SOLUTION: a, d, f, g, h, i, m, o, r, s, t, w

PROBLEM: ['4313', 'y', 'f', 'o', '8963', 'e', 'd', '4155', 's', '165', '775', 's', 'l', 'w', '7613', 'p', 'o', '3365']

SOLUTION:
d, e, f, l, o, p, s, w, y