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: ['421', '99', '115', 'x']

SOLUTION: 1, 2, 4, 5, 9

PROBLEM: ['109', 'b']

SOLUTION: 0, 1, 9

PROBLEM: ['t', '103', '349', '203', 'b', 'z', 'i', '337', 'y', '137', '77', 'p', 'k']

SOLUTION:
0, 1, 2, 3, 4, 7, 9