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: ['t', 'x', '1699', '8727']

SOLUTION: t, x

PROBLEM: ['5737', 'b', 'e', 't', '7419', 'n', 'y', '5225', '6485', 'b', '1343']

SOLUTION: b, e, n, t, y

PROBLEM: ['3347', '7827', 'u', '1363', '711', '8247', '9187', '2783', '2485', '5759', 'k']

SOLUTION:
k, u

