
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
Linlin fills a glass with pure milk. The first time she drinks $\frac{1}{3}$ of the milk, then fills the glass with soy milk and stirs well. The second time, she drinks $\frac{1}{3}$ of the mixture, refills the glass with soy milk, and stirs well again. She repeats this process. What fraction of the total amount of pure milk will Linlin have drunk after the fourth time?

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