You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Charles Perez here.

ASSISTANT: Charles Perez. How can I help you?

USER: I need to book a flight from DCA to BOS, can you help me?

ASSISTANT: May I know the travel dates please?

USER: My journey dates are June 02 to 04.

ASSISTANT: Do you have any airline preferences?

USER: No.

ASSISTANT: Do you have any class preference?

USER: I am comfortable with any class.

ASSISTANT: Is there any time concern?

USER: My return time is in evening.

ASSISTANT: May I know the connection limit.

USER: I need one stopover.

ASSISTANT: Are there any other concerns?

USER: No, thanks for asking.

ASSISTANT: Give me a moment.

USER: Sure.

ASSISTANT: Thank you for waiting. I regret to inform that there are no flights on your route with your requirements.

USER: Ok, no issues. Thank you for information.

ASSISTANT: Thank you for approaching us.