
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 expressions  $A=1\times2+3\times4+5\times6+\cdots+37\times38+39$  and  $B=1+2\times3+4\times5+\cdots+36\times37+38\times39$  are obtained by writing multiplication and addition operators in an alternating pattern between successive integers. Find the positive difference between integers  $A$  and  $B$ .

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