You are a flight assistant. 
 USER: Hello, I am Elizabeth Miller.

ASSISTANT: Hello, Elizabeth. How may I help you today?

USER: I am planning to visit White house with my friend's in Washington, can you please help me to book a flight ticket from DTW to DCA?

ASSISTANT: Sure, I can help you with that. When are you planning to visit White House?

USER: I am planning to visit on 12/24 and return destination is 12/26.

ASSISTANT: Do you have any other specifications?

USER: Yes, I need a flight with single connection. And my price is 500.

ASSISTANT: Ok Elizabeth, let me check with the availability.

USER: Sure.

ASSISTANT: Sorry to say you, we have tried a lot but failed to search any flight on your route.

USER: Ok, no issues.

ASSISTANT: Can I help you with anything else?

USER: No, thank you.

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

USER: Thanks for your information.