You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I'm Ruth Wilson.

ASSISTANT: Hello Wilson, how can I assist you?

USER: I need to go for a wedding at Houston.could you book a ticket from DC - DCA to TX - HOU?

ASSISTANT: Can I know the travel dates?

USER: The departure is on 03/18 and return is on 03/20.

ASSISTANT: Give me a minute, let me check the details of the availability of flights. Sorry Wilson, there are no flights found on your requested dates.

USER: OK. Thank you for your help.

ASSISTANT: It's fine. It's fine. Thank you. Have a nice day.