You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Can you please help me in booking a flight ticket from OAK to IAD?

ASSISTANT: Sure, please share me your travelling dates?

USER: I would like to travel on July 15 and return on July 17.

ASSISTANT: Do you have any class preference?

USER: No, I am comfortable with any of the class.

ASSISTANT: Is there any connection limit?

USER: I prefer to fly in connecting flight.

ASSISTANT: May I know your name?

USER: Myself Charles Johnson.

ASSISTANT: Sorry, there were no flights with your given details.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.