
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 $x_1$, $x_2$, $x_3$, $x_4$, $x_5$, $x_6$, $x_7$ be natural numbers, and $x_1 < x_2 < x_3 < \ldots < x_6 < x_7$, also $x_1 + x_2 + x_3 + x_4 + x_5 + x_6 + x_7 = 159$, then the maximum value of $x_1 + x_2 + x_3$ is.

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