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: ['i', 's', 'f', 'i', '2293', '245', '4983', 'h', 'h', '6203', '8703', '1613', 'h', 'o', '3635', '8069', '2829', '1939', 'u', 'm', '5305', 'n', 'k', '9367', 'u']

SOLUTION: f, h, i, k, m, n, o, s, u

PROBLEM: ['7799', '8163', '3389', 'x', 'k', 'm', '6085', 'f', '1131']

SOLUTION: f, k, m, x

PROBLEM: ['4619', 'w', '7293', 'h', 'o', '9821', '6099', '969', '5009', 'a', '4525']

SOLUTION:
a, h, o, w