You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: Please book me a flight ticket from IAD to OAK to meet my family.

ASSISTANT: Sure, may I know your travel dates?

USER: I have planned to travel on May 15th and return on May 17th.

ASSISTANT: Do you have any specifications?

USER: I prefer direct flight.

ASSISTANT: May I know your name?

USER: Brenda Martinez.

ASSISTANT: Ok, please wait a minute.

USER: Ok.

ASSISTANT: Sorry, there were no flights found on your route.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.