
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
A company uses an interest-free loan from a bank to invest 4 million yuan in introducing a high-tech production line, expecting to earn a profit of 1 million yuan per year. However, additional maintenance and repair costs for this production line are 100,000 yuan for the first year and increase by 50,000 yuan each subsequent year. How many years are needed at least to recover this investment? (i.e., the total profit is not less than the total expenditure)

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