You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: Robert Allen here. I want to visit SFO. Can you book my ticket from IAD?

ASSISTANT: May I know your travelling dates please?

USER: My travelling dates are from 02/06 to 02/08.

ASSISTANT: I am sorry no flights found on your route.

USER: That's fine. Thank you for your time.

ASSISTANT: Thank you for choosing us.