
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
Analyzing natural numbers with 4 digits:

a) How many of them have all different digits?

b) How many have the digit 1 exactly once and all other digits are different?

c) How many have the digit 1?

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