You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: I am Lisa Hill, want to travel from LGA to DCA. Please help me in booking my ticket.

ASSISTANT: Sure, may I know your trip dates?

USER: Sure, my travelling dates are from 03/23 to 03/25.

ASSISTANT: Sorry, on these dates there is no flights available.

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

ASSISTANT: Most welcome,.