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: ['8821', '9833', 'l']

SOLUTION: l

PROBLEM: ['2799', '7519', '345', 'e', 'l', '9369', '4703', '4111']

SOLUTION: e, l

PROBLEM: ['8631', 'e', 'j', 's', '6389', 'v', 'n', '2349', 'i', 'd', '4761', 'j', '4169', '5029', 'i', 'f', '1083', '6037', 'q', '5591', '3237', '1629', '4353', 'd', 'z', 'd', 'n', '731', '5937']

SOLUTION:
d, e, f, i, j, n, q, s, v, z