
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
Please fill in the subsequent letter or number in the blank space from a theoretical or logical perspective.  
①A, D, G, J,     .            ②21, 20, 18, 15, 11,     .  
③8, 6, 7, 5, 6, 4,     .      ④18, 10, 6, 4,     .

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