
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
A fleet has 7 vehicles, and now 4 vehicles need to be dispatched in a certain order to carry out tasks. It is required that vehicles A and B must participate and vehicle A must go out before vehicle B. How many different dispatch plans are there? (Answer with a number)

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