
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 two non-collinear vectors $i$ and $j$, it is known that $\overrightarrow{AB} = i + 2j$, $\overrightarrow{CB} = i + \lambda j$, and $\overrightarrow{CD} = -2i + j$. If points A, B, and D are collinear, then the value of the real number $\lambda$ is ______.

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