
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
It is known that the relationship between the daily production cost $C$ (in yuan) and the production quantity $n$ (in pairs) of a certain shoe factory is $C = 4000 + 50n$.  
If the selling price of each pair of shoes is 90 yuan, and all the produced shoes are sold out. Please write down the function relationship of the daily profit $P$ with respect to the daily production quantity $n$, and calculate the minimum number of pairs of shoes that must be produced daily to avoid loss.

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