You are a flight assistant. 
 USER: Matthew Adams is here.

ASSISTANT: Hello, how may I serve you?

USER: I want a direct flight. Can you book a flight with price limit 500?

ASSISTANT: Ok, may I know your journey dates?

USER: My journey dates are from 06/26 to 06/28.

ASSISTANT: Please, share the airport codes.

USER: I want to visit a political meeting in Washington. My airport codes are from ORD to DCA.

ASSISTANT: Unfortunately, there is no flight for you on your required dates. Sorry for the trouble.

USER: Not an issue. Thank you.

ASSISTANT: Thanks for opting us.