You are a helpful assistant that can solve the given question step by step with the help of the wikipedia search tool and python interpreter tool. Given a question, you need to first think about the reasoning process in the mind and then provide the answer. During thinking, you can invoke the wikipedia search tool to search and python interpreter tool to calculate the math problem for fact information about specific topics if needed. The reasoning process and answer are enclosed within <think> </think> and <answer> </answer> tags respectively, and the search query and result are enclosed within <search> </search> and <result> </result> tags respectively. For example, <think> This is the reasoning process. </think> <search> search query here </search> <result> search result here </result> <think> This is the reasoning process. </think> <python> python code here </python> <result> python interpreter result here </result> <think> This is the reasoning process. </think> <answer> The final answer is \[ oxed{answer here} \] </answer>. In the last part of the answer, the final exact answer is enclosed within oxed{} with latex format.
system
On the Island of Knights and Knaves, knights always tell the truth, and knaves always lie. One day, a traveler questioned seven inhabitants of the island.

- "I am a knight," said the first.
- "Yes, he is a knight," said the second.
- "Among the first two, at least 50% are knaves," said the third.
- "Among the first three, at least 65% are knaves," said the fourth.
- "Among the first four, at least 50% are knights," said the fifth.
- "Among the first five, at least 40% are knaves," said the sixth.
- "Among the first six, at least 65% are knights," said the seventh.

Determine how many knights there are among them.
user
5
rule
On the Island of Knights and Knaves, knights always tell the truth, and knaves always lie. One day, a traveler questioned seven inhabitants of the island.

- "I am a knight," said the first.
- "Yes, he is a knight," said the second.
- "Among the first two, at least 50% are knaves," said the third.
- "Among the first three, at least 65% are knaves," said the fourth.
- "Among the first four, at least 50% are knights," said the fifth.
- "Among the first five, at least 40% are knaves," said the sixth.
- "Among the first six, at least 65% are knights," said the seventh.

Determine how many knights there are among them.
train