You are a flight assistant. 
 USER: Hello, I'm John Hall.

ASSISTANT: Hello Hall. How may I assist you today?

USER: During rainy season I would like to go to my brother's home, so could you please book a ticket from LAS to DCA?

ASSISTANT: Sure, may I know your trip dates?

USER: I would like to travel on 01/06 and return on 01/08.

ASSISTANT: John sorry to say this no flights as per your details.

USER: That's ok. Thank you.

ASSISTANT: You are welcome.