
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
Let's say the number $\mathrm{A}$ hides within it the number $\mathrm{B}$ if several digits can be removed from A to obtain B (for example, the number 123 hides the numbers 1, 2, 3, 12, 13, and 23 within it). Find the smallest natural number that hides the numbers $121, 221, 321, \ldots, 1921, 2021, 2121$.

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