You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am Matthew White. I am planning to visit from DCA to PHX.Can you help me out?

ASSISTANT: On what dates you want to travel, Matthew White?

USER: My travelling dates are 12/18 to 12/20.

ASSISTANT: There is no flight available on 12/18.

USER: That's fine. Thank you for you help.

ASSISTANT: Thanks for reaching us.