You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

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

ASSISTANT: Can I know your travelling dates?

USER: My travel dates are Aug, 7 and Aug, 9.

ASSISTANT: Do you have any specification?

USER: I need connecting flight.

ASSISTANT: Can I know your name?

USER: John Johnson here.

ASSISTANT: Sorry, there is no flight with your travelling dates.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you.