You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Please help me to book a flight ticket from DEN to DFW.

ASSISTANT: Sure, I will help you in booking the ticket. May I know your travelling dates please?

USER: I will start on June, 21 and return on June, 23.

ASSISTANT: Do you have any other specifications?

USER: I need direct flight.

ASSISTANT: Please help me with your name for booking.

USER: Jonathan Jones.

ASSISTANT: Sorry for this inconvenience, I could not find any flight with your requirements.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for reaching us.