You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you?

USER: Could you book my ticket from OAK to IAD?

ASSISTANT: Sure, I will help you. Please send your travelling dates.

USER: My trip dates are July 12 and July 14.

ASSISTANT: Do you have any preferences?

USER: I want to depart in the morning.

ASSISTANT: May I know your name please?

USER: Robert Parker here.

ASSISTANT: Sorry, there is no flight available with your requirements.

USER: No problem, thank you.

ASSISTANT: You are welcome, have a nice day.