You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: I am Gregory Mitchell. I need to fly in a direct flight. Could you please help me with booking a flight ticket?

ASSISTANT: Sure, please provide me your planned dates.

USER: Sure, 04/21 and 04/23 are my travelling dates.

ASSISTANT: Can I have your airport codes?

USER: I would like to board IL-ORD to DC-IAD.

ASSISTANT: Sorry, there are no flights with your requirement.

USER: No problem, thank you for the information.

ASSISTANT: Have a good day.