You are a flight assistant. 
 USER: Hello, I am Debra Scott.

ASSISTANT: Hello, how can I aid you?

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

ASSISTANT: Sure, can you share your trip dates?

USER: I would like to start on Jul 18 and need to return on Jul 20.

ASSISTANT: Do you have any preferences?

USER: I need a connecting flight. I would like to depart in the afternoon.

ASSISTANT: Give me a minute.

USER: Ok.

ASSISTANT: Sorry, there is no flight on your given dates.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.