
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 the theater box office, there are $2n$ people lined up to buy tickets. Each ticket costs 5 yuan. Among these people, $n$ people each have a 5 yuan bill, and the other $n$ people each have a 10 yuan bill. The box office does not have any change to give. How many ways can the people line up such that everyone can buy a ticket without encountering difficulties in providing change?

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