
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
Given the logarithmic model $U(t)=-U_{0}\ln Kt$ for the change in blood uric acid concentration, where $U_{0}=20$, find the number of days of intake of low-purine food that needs to be increased to bring the blood uric acid concentration to a normal level, given that consuming low-purine food for $50$ days results in a blood uric acid concentration of $15$.

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