You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Could you please help in booking my flight ticket?

ASSISTANT: Sure, could you provide your name for further processing?

USER: I'm Dorothy Edwards.

ASSISTANT: Ok Dorothy, can you please provide the city names?

USER: My origin airport is DC - DCA and destination airport is DC - DCA.

ASSISTANT: Ok, can you please mention your travel dates?

USER: My travel dates are 07/19 and 07/21.

ASSISTANT: Ok, please wait a moment.

USER: OK.

ASSISTANT: Sorry, cannot found any flights under your requirements.

USER: OK. Thank you for your information.

ASSISTANT: You are welcome. Have a nice day!.