You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am Cynthia Campbell, want to travel from DCA to SFO. Please help me in booking my ticket.

ASSISTANT: Sure, on which dates you are willing to travel?

USER: My travelling dates are from 08/21 to 08/23.

ASSISTANT: On this dates, there is no reservation found.

USER: It's ok, thank you for your help.

ASSISTANT: Most welcome.