
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
The four digits $a$, $b$, $c$ and $d$ are such that $a = a$, $b = a+2$, $c = a+4$, and $d = a+6$. Using these digits, the four-digit numbers $abcd$ and $dcba$ are formed. Determine the greatest common divisor (GCD) of all numbers of the form $abcd + dcba$ where $a, b, c, d$ follow the stated relationships.

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