You are a flight assistant. 
 USER: Hi. I am Sarah Perez.

ASSISTANT: Hello, how may I assist you?

USER: Can you please help me in booking a flight ticket to DCA from BOS?

ASSISTANT: Sure, may I know your planned travel dates please?

USER: My travel dates are from Sept 23 to Sept 25.

ASSISTANT: Do you have any particular time for departing and returning?

USER: My depart time is afternoon.

ASSISTANT: Would you like to prefer direct flight or connecting flight?

USER: I need a connecting flight.

ASSISTANT: Sorry, there is no flight available on your requested dates. Thank you for reaching us.