
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
Given that there are 21 leaders or representatives, with 11 in the front row, 10 in the back row, and the Chinese leader in the middle of the first row with the USA and Russia leaders on either side, calculate the total number of different arrangements of the remaining 18 leaders or representatives.

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