
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 positive four-digit number has thousands digit $a$, hundreds digit $b$, tens digit $c$, and units digit $d$ satisfying the relation $(a-b)(c-d)<0$, then it is called a "Rainbow Four-Digit Number", for example, 2012 is a "Rainbow Four-Digit Number". How many "Rainbow Four-Digit Numbers" are there among positive four-digit numbers? (Answer with a number directly)

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