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: ['397', '287', '401', '97']

SOLUTION: 0, 1, 2, 3, 4, 7, 8, 9

PROBLEM: ['z', 'e', '75', '379', 'c', 'f', 'g', '381', 'l', 'u', '197', '489']

SOLUTION: 1, 3, 4, 5, 7, 8, 9

PROBLEM: ['f', 'a', '71', '207', 'l']

SOLUTION:
0, 1, 2, 7