You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I want to visit Boston, can you book a ticket from IAD to BOS?

ASSISTANT: May I know your travel dates?

USER: My travel dates are 07/29 and 07/31.

ASSISTANT: May I know your name to proceed further?

USER: My name is Justin Johnson.

ASSISTANT: Based on your request, there is no flight. Sorry for this inconvenience.

USER: No issues.

ASSISTANT: Thanks for contacting us.

USER: Welcome.