You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you?

USER: I am Margaret Evans. Can you help me to book a flight on 04/12 and 04/14?

ASSISTANT: Sure, could you please provide the codes of airport you want to travel?

USER: My source and destination airport codes are IAH and DEN.

ASSISTANT: Ok, please wait a moment. Sorry to say, no flights were found on your route.

USER: Ok, no issues. Thank you for your time.

ASSISTANT: Thank you for reaching us, have a nice day.