
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
In front of a cinema box office, there are $2n$ people in line, each wanting to buy a movie ticket costing 5 yuan. Among these people, $n$ have a 5 yuan bill each, and the remaining $n$ have a 10 yuan bill each. The box office initially has no money. How many different ways can the order of the queue be arranged so that every person can successfully buy a movie ticket?

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