You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: Can you help me to book a flight ticket from SFO to DCA?

ASSISTANT: Sure, may I know your travel dates?

USER: Feb, 11 and Feb, 13 are my travel dates.

ASSISTANT: Do you have any specifications?

USER: I need to travel in business class only with direct flight.

ASSISTANT: May I know your name?

USER: Barbara Collins here.

ASSISTANT: Ok, please wait a minute.

USER: Sure.

ASSISTANT: Sorry, there were no flights found on your route.

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

ASSISTANT: Thank you.