
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
Chubby creates a different nonstandard checkerboard with 29 squares on each side. The checkerboard maintains a black square in each corner and alternates between red and black squares in each row and column. Determine the number of black squares on this checkerboard.
A) 419
B) 420
C) 421
D) 422
E) 423

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