You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I need you to book a flight ticket from DCA and LAS.

ASSISTANT: Ok, may I know your planned travel dates?

USER: June 11 and 13 are my planned travel dates.

ASSISTANT: Do you want connecting flight?

USER: Yes, I do need it.

ASSISTANT: Is there any class preference?

USER: I prefer to fly in a economy class.

ASSISTANT: Do you have any other requirements?

USER: Nothing much to state.

ASSISTANT: May I know your name please?

USER: My name is Benjamin Robinson.

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

USER: That's ok. Thank you.

ASSISTANT: Thank you for opting us.