You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. May I know your name please?

USER: This is Mary Adams.

ASSISTANT: What can I do for you Mary?

USER: Could you please book a flight ticket on these days 04/02 and 04/04.

ASSISTANT: Sure, please let me know the source and destination codes you have planned for?

USER: I would like to travel from TX-DFW to DC-DCA.

ASSISTANT: Sorry, there are no flights available from DFW on 04/02.

USER: Thank you for your information.

ASSISTANT: Thank you for reaching us.