Teacher: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.
Teacher: Now, understand the problem? Solve this instance: ['71', 'm', 's', 'x', 'n', 'a', '103', '275', '353', 'a', 'k', 'b', '71', '459']
Student:
0, 1, 2, 3, 4, 5, 7, 9