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: ['437', '377']

SOLUTION: 3, 4, 7

PROBLEM: ['159', 'y', '369', 'r', '341', '23', 's', '209', 'l', 's', '473']

SOLUTION: 0, 1, 2, 3, 4, 5, 6, 7, 9

PROBLEM: ['b', '177', '291', '277', '37', 'a', '279']

SOLUTION:
1, 2, 3, 7, 9