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: ['1121', 'j', '1433', 'g', 'l', '1479', '1699', 'j', 'a', '8507', 'd', 'a', '5229', 'k', 'x', '4549', 'e', 'p', '1367', 'u', 'd', '785', '215', 'e', 'f', 'a', '101', '7575', '7965', 'p', 'i', '5637', '1005', 'i', 'y', '181', 'r']

SOLUTION: a, d, e, f, g, i, j, k, l, p, r, u, x, y

PROBLEM: ['x', 'w', 'y', '6459', 'n', '4743', 's', 'h', '859', 'p', '6427', '7577', 'z', 'f', 'a', 'o', 'p', '3019', '8501', 'z', 'c', 'p', 'w', 'i', '3917', 'b', 'a', '5565', 'n', 'd', '2031', '3595', '667', '8481', 'q', '7603', '8229', 'y', '9119', 'r', 'b', '8059', 'u', '1849', 'z']

SOLUTION:
a, b, c, d, f, h, i, n, o, p, q, r, s, u, w, x, y, z