You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I am Karen Davis, can you help me booking flight on 08/26?

ASSISTANT: Sure, let me know your airport codes?

USER: My travelling airport codes are DCA to LGA.

ASSISTANT: Do you need a return ticket?

USER: Yes, I am going to start my journey on 08/24.

ASSISTANT: Sorry, there is no flight is available for you.

USER: Oh! It's ok, no problem.

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

USER: Thank you for your services.