You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to visit San Francisco, can you please book the ticket from OAK to SFO?

ASSISTANT: Sure, may I know the travelling dates?

USER: Sure, my planned departure and return travel dates are 15th and 17th of Aug.

ASSISTANT: Do you have any connection limit?

USER: I prefer single connected flight to travel.

ASSISTANT: Is there any other requirements?

USER: I want to travel in major airlines only.

ASSISTANT: May I know your name?

USER: My name is Eric Lewis.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry, no flights found with your chosen dates.

USER: That's ok, thank you for giving the information anyways.

ASSISTANT: Thank you for availing us.