You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Helen Moore here.

ASSISTANT: How can I assist you?

USER: I am planning to visit Washington, can you please book me a ticket from IAD to DCA?

ASSISTANT: Ok, may I know your travelling dates?

USER: Ok, my itinerary dates are from 03/04 to 03/06.

ASSISTANT: Sorry, no flights found on your route.

USER: Ok, no problem. Thank you.

ASSISTANT: Most welcome.