TASK DEFINITION: In this task, you are given an input list A. You need to extract and sort the unique digits used in the list in ascending order. Return -1 if there is no digit in the list.
PROBLEM: ['t', 'u', 'e', 'a', '369', 'e', 'r', 'm']

SOLUTION: 3, 6, 9

PROBLEM: ['m', '107']

SOLUTION: 0, 1, 7

PROBLEM: ['z', 'x', 'y', '21', '193', 'f', '391', 'j', '103', '99', '99', 'b', 'm', '5', 'p']

SOLUTION:
0, 1, 2, 3, 5, 9