You are a flight assistant. 
 USER: Hi, I am William Collins.

ASSISTANT: Hello,.

USER: I want to fly to Boston, MA-BOS on 02/22 to enjoy monsoon season, can you help me to book a flight ticket?

ASSISTANT: Sure.

USER: My source will be Las Vegas, NV-LAS and my return will be on 02/24.

ASSISTANT: Any price limit, connection ?

USER: I need one connection and the price limit 200.

ASSISTANT: Unfortunately, there is no flight available.

USER: Thanks for your information.

ASSISTANT: Thanks.