You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Frank Nelson here.

ASSISTANT: How can I help you?

USER: I want to visit Disney world, can you please book a ticket from ORD to DCA?

ASSISTANT: Sure, I will help you to book a flight ticket. Can you please share me your travelling dates?

USER: Sure, my planned departure and return travel dates are 22nd and 24th of August.

ASSISTANT: Please give me a moment.

USER: I want to depart on the evening, search according to that.

ASSISTANT: Sorry, no flights are available on your route.

USER: Oh! That's ok, thank you for giving the information.

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