You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I'm Alexander Mitchell.

ASSISTANT: How can I help you?

USER: I want to attend an event in Washington. Can you book a ticket from BOS to IAD?

ASSISTANT: Ok, could you please mention your travel dates?

USER: The departure is on 01/21 and return is on 01/23.

ASSISTANT: Ok, please wait a while. Sorry Alexander, no flights have been found on your details.

USER: That's really sad. Anyways, thank you for your help.

ASSISTANT: Thank you for approaching us.Have a nice day.