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: ['b', 't', '2199', 'e', 'i', '1883', '5137', '8495', 't', '7377', 'm', '7665', '2009', 'o', '3757', 'm', '861', 'm', 'l', '9229', 'c', 'r', 'q', 'i', 'm', '705', 'b', '4301', 'd', 'l', 'f', '5485', 'h', 'p', '4529', '7879', 'f', 'b', 'm']

SOLUTION: b, c, d, e, f, h, i, l, m, o, p, q, r, t

PROBLEM: ['6585', 'i', 'p', '5623', '3557', '8011', 'c', '6389', 'h', 'h', 'd', '1823', '5567', 'v', 'p', 'x', 'c', '2161', '3649', 'o', '6227', 'f', '9975', 'd', 'm', '2587', 'o', 't', 'k', '7637', 'm', 'l']

SOLUTION: c, d, f, h, i, k, l, m, o, p, t, v, x

PROBLEM: ['n', '9885', 'b', 'i', 's', 'c', '7707', '513', 'n', 'w', '1087', 'u', '4071', 't', 'd', '3877', '6353', '8103', '1087', '7733', 'a', '6019', 'k', '8837', '4151']

SOLUTION:
a, b, c, d, i, k, n, s, t, u, w