You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Eric Perez, want to travel from DEN to IAD. Please help me.

ASSISTANT: Sure, on which dates you are planning to travel?

USER: Sure, my travelling dates are from 11/04 to 11/06.

ASSISTANT: Sorry, there is no flights available.

USER: It's ok, thank you.

ASSISTANT: Most welcome.