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

ASSISTANT: Hello, how may I help you today?

USER: I want to book a flight ticket from PHX to DCA. Can you help me with direct flight?

ASSISTANT: Sure,When are you planning to make your journey?

USER: My planned dates are from 06/17 to 06/19.

ASSISTANT: OK, thanks for the details.

USER: Ok.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting. Sorry to inform you there is no flights found with your specifications.

USER: Ok, No problem.

ASSISTANT: Thanks for reaching us.

USER: Thanks for choosing us.