You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: This is Jack Baker.

ASSISTANT: How can I help you?

USER: There is a cancer patient with me his last wish is to travel from DCA to IAH, can you help me in booking a ticket?

ASSISTANT: Sure, please tell your travelling dates?

USER: My travelling dates are from 12/18 to 12/20.

ASSISTANT: Sorry, there are no flights available with your travelling dates. Do you want to have any more information please?

USER: No, thank you for helping me out.

ASSISTANT: Thank you and have a nice day.