
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 4x4 grid is to be filled with four A's, four B's, four C's, and four D's such that each row and column contains one of each letter. If 'A' is placed in the upper left corner, calculate the number of possible arrangements.

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