You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I am John Thomas need to book a flight ticket with single connection and departure time in the evening, can you please help me in booking?

ASSISTANT: Sure, I am here to help.

USER: Thank you.

ASSISTANT: Please share your source and destination airport codes.

USER: My source is at IL-ORD and destination is at DC-IAD.

ASSISTANT: When are you willing to travel?

USER: I am willing to start on Nov 18 and need to return on Nov 20.

ASSISTANT: Thank you, please wait for a while.

USER: Ok.

ASSISTANT: Sorry to inform you that there is no flight available which departs in the evening.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for checking it with us.