
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
If $a$, $b$, $c$, $d$ are integers, $b$ is a positive integer, and satisfy $a+b=c$, $b+c=d$, $c+d=a$, then the maximum value of $a-2b+3c-4d$ is ______.

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