You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: Could you please help me in booking a flight ticket from IAD to SFO?

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

USER: My travelling dates are July 05 and July 07.

ASSISTANT: Do you have any other specifications?

USER: I need a direct flight. And I prefer an economy class.

ASSISTANT: Please help me with your name for booking.

USER: My name is Dennis Wilson.

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

USER: Not an issue, thank you for the information.

ASSISTANT: Thank you for reaching us.