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: ['6643', '6757', 'h', '1033', 's', 'c', '2003', 'p', '5483', 'f']

SOLUTION: c, f, h, p, s

PROBLEM: ['t', 'a', '2481', '2841', 'a', '2871', 'm', '4435', 'g', '8201', '4351', '9045', 'o']

SOLUTION: a, g, m, o, t

PROBLEM: ['5671', '4893', '5435', 'd', 'l', '2633', 'h', 'k', 'w', 'u', 'c', '2629', 'w', 'm', 'w', '9903', '8495', '7409', '8727', '5911', '6823', '9497', '1117', 'c', 'o', 'r', 'o', '4553']

SOLUTION:
c, d, h, k, l, m, o, r, u, w