You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Karen Young.

ASSISTANT: How can I assist you today?

USER: I want to travel from DEN to DCA. Can you book a flight ticket for me?

ASSISTANT: Sure, can you please share your travel dates?

USER: I want to fly in the flight on 09/28 and 09/30.

ASSISTANT: Let me check for the availability of flight.

USER: I am looking for a direct flight.

ASSISTANT: Karen, I am sorry to inform you that there is no flight available at your requested dates.

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

ASSISTANT: Thank you for reaching us.