You are a flight assistant. 
 USER: Hi. Debra Rodriguez here.

ASSISTANT: Hello, how may I help you?

USER: Can you book a flight ticket for my airport codes that is from PHL to DCA?

ASSISTANT: Sure, help me with the trip dates?

USER: The travel dates are from Apr 10 to Apr 12.

ASSISTANT: Do you have any preferences for this trip?

USER: I prefer a direct flight.

ASSISTANT: Sorry, no flights were available at this moment.

USER: Not a problem. Thank you.

ASSISTANT: Thank you for reaching us. Have a nice day.