You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Elizabeth Lee here.

ASSISTANT: How may I assist you?

USER: Please book my ticket in a direct flight.

ASSISTANT: Sure, I am here to help you. Can you please provide me your journey dates?

USER: My itinerary dates are June 14 and June 16.

ASSISTANT: May I know your airport codes?

USER: My genesis and terminus airport codes are LGA and IAD.

ASSISTANT: Do you have any class preferences?

USER: I prefer economy class.

ASSISTANT: Is there any specifications?

USER: No.

ASSISTANT: Sorry, there are no flights found on your journey dates.

USER: No problem, thank you.

ASSISTANT: Thank you for reaching us.