You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you today?

USER: I would like to meet my friend at Washington-DC, please help me to book my flight ticket from DFW to DCA.

ASSISTANT: Sure, I will help you with that. May I know your planned travel dates?

USER: Thank you. I will depart on Apr 29th and return back on May 1st.

ASSISTANT: Would you like to travel in a connecting flight or direct flight?

USER: I prefer for a connecting flight.

ASSISTANT: Do you have any class preference?

USER: Any class is fine for me.

ASSISTANT: Is there any other requirements regarding your journey?

USER: I also prefer for a normal-cost airline.

ASSISTANT: Sorry, there are no flights found on this route as per your travel dates.

USER: Sad to hear that. Anyway, thank you for the information.

ASSISTANT: May I know your name for documentation purpose?

USER: My name is David Mitchell.

ASSISTANT: Thank you for reaching us, have a great day.

USER: You are welcome.