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: ['23', '81', 'f', 'e', 'n', 'e', 'n', 'p', 'm', '131', 'n', '367', '137', 'e']
Student:
1, 2, 3, 6, 7, 8