Instructions: 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.
Input: ['u', 'n', '155', '87', '353', '489', '489', '201', 'u']
Output:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
0, 1, 2, 3, 4, 5, 7, 8, 9