
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system

Points A and B are 999 km apart, with 1000 milestones along the way. Each milestone indicates the distance to points A and B in the format (distance to A, distance to B), such as (0, 999), (1, 998), (2, 997), ..., (997, 2), (998, 1), (999, 0). How many of these milestones display exactly two different digits on the distances to A and B?

Present the answer in LaTex format: \boxed{Your answer}
user