You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I guide you for today?

USER: Can you help me in booking a flight from IAD to SFO?

ASSISTANT: Can you please share on what dates you are willing to travel?

USER: I like to travel on July 17 to 19.

ASSISTANT: Are you looking for a connecting flight or direct flight?

USER: I prefer travelling in single connection.

ASSISTANT: Do you have any class preferences?

USER: I want to travel on economy class.

ASSISTANT: Do you have any other requirements that you are looking for?

USER: No.

ASSISTANT: Can you please provide your name to proceed further?

USER: I am Justin Evans.

ASSISTANT: Sorry, there are no flights available at your request.

USER: That's ok, thank you.

ASSISTANT: Thank you for contacting us, have a nice day.