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', '1129', 'f']

SOLUTION: f, i

PROBLEM: ['e', 'n', 'y', 'f', 'l', 'h', '455', 'y', '591', 'm', '9041', 'b', 'b', 'o', '4215', '5009', 'o', 'a', '4369', 'u', '6911', '4825', 't', 'k', '6063', '2939']

SOLUTION: a, b, e, f, h, k, l, m, n, o, t, u, y

PROBLEM: ['l', 'b', 'h', '1513', '1833', '17', 'b', '4211', '3055', 'j', 'l', '471']

SOLUTION:
b, h, j, l