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.

Q: ['149', '129', 'k']

A: 1, 2, 4, 9
****
Q: ['y', 'o', '287', 'm', 's', '61']

A: 1, 2, 6, 7, 8
****
Q: ['w', 'u', '61', 'l', 'k']

A:

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
1, 6
****
