You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Dennis Moore here. Can you book a flight ticket from IAD to BOS?

ASSISTANT: Dennis Moore, I am here to help you for this. When you are willing to travel?

USER: My travel dates are 09/22 and 09/24.

ASSISTANT: Do you have any airline preference?

USER: No.

ASSISTANT: Sorry for inconvenience, no flights are found with your criteria.

USER: That's ok, no problem.

ASSISTANT: Thank you very much for reaching us.

USER: Thank you.