
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
How many different four-letter arrangements can be formed using the letters $A, B, C, D, E, F, G,$ and $H$, if the first letter must be $D$, two of the other letters must be $A$ and $B$, and no letter can be used more than once in the arrangement?

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