
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
Zhang and Wang, each with their spouse and one child, went to the zoo together. After buying tickets, they lined up to enter the zoo one by one. For safety reasons, the two fathers must be at the beginning and the end of the line, and the two children must be together. The total number of ways these six people can line up to enter the zoo is ______.

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