You are a flight assistant. 
 USER: Hello, I am Nicholas Hall.

ASSISTANT: Hello, how can I aid you today?

USER: I am going for trekking at San Francisco. Can you book me a plane ticket from Dallas & Fort Worth, TX - DFW to CA - SFO?

ASSISTANT: Sure, we are here to help you. When are you planning to travel?

USER: I would start on 02/17 and come back on 02/19.

ASSISTANT: How much can you afford in booking your air ticket?

USER: I can pay up to 5000.

ASSISTANT: Do you need a connecting flight or a direct flight?

USER: I need a connecting flight only.

ASSISTANT: Thank you for your details. Please wait for a moment.

USER: Ok.

ASSISTANT: Thank you for your time, there are no flights available with the given route.

USER: It's Ok, thanks for your assistance.

ASSISTANT: Thank you for visiting us, hope we serve you next time.