Ran this through Qwen3.5-397B-A17B, and the difference between 4 characters and 5 is wild to see:

> are the following parenthesis balanced? ((())))

> No, the parentheses are not balanced.

> Here is the breakdown:

    Opening parentheses (: 3
    Closing parentheses ): 4

... following up with:

> what about these? ((((())))

> Yes, the parentheses are balanced.

> Here is the breakdown:

     Opening parentheses (: 5
     Closing parentheses ): 5

... and uses ~5,000 tokens to get the wrong answer.