
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 there be $k$ natural numbers $a_1, a_2, \ldots, a_k$ satisfying the condition $1 \leq a_1 < a_2 < \ldots < a_k \leq 50$, and the sum of any two numbers cannot be divisible by 7. The maximum value of $k$ is     .

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