You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you?

USER: My name is Helen Roberts. I'm planning to visit Lincoln Memorial on 05/26, can you please help me in booking a ticket?

ASSISTANT: Sure, can I know the details of travel?

USER: It's from OAK to IAD. My return date is 05/28.

ASSISTANT: I'm sorry, there are no flights matching with your dates.

USER: That's fine.

ASSISTANT: Thank you, have a good day.

USER: Thank you for your time.