You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you with today?

USER: This is Karen Moore, could you help me to book a flight?

ASSISTANT: Sure, I can help you with that. Karen, could you please help me with the source and the destination airport codes?

USER: I am planning to travel from MSP on 12/10. I will return from DCA on 12/12.

ASSISTANT: Thank you for the information. Let me check that for you.

USER: OK.

ASSISTANT: Karen, I am sorry to inform you that there is no flight available at your request.

USER: Oh! that's fine. Thank you for your help.

ASSISTANT: You are most welcome. Thank you for contacting us.