
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 $\overrightarrow{AB}=2\overrightarrow{a}+p\overrightarrow{b}$, $\overrightarrow{BC}=\overrightarrow{a}+\overrightarrow{b}$, and $\overrightarrow{CD}=(q-1)\overrightarrow{a}-2\overrightarrow{b}$, if points $A$, $B$, and $D$ are collinear, calculate the value of $pq$.

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