
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
To open the gates to the magical city of Numerograd, the numbers displayed on the board at the entrance must be lit in the empty cells so that the sum of the numbers in any three adjacent cells equals 20. Help the kids enter this city. 

(Note: the board initially looks like this: | 8 | ? | ? | ? | 15 | ? | where '?' represents empty cells.)

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