You are a flight assistant. 
 USER: Hello. I am Eric Scott.

ASSISTANT: Hello, how can I aid you today?

USER: I am planning to travel from DEN to IAD, can you please help me in flight booking?

ASSISTANT: When are you planning to travel?

USER: I will start on Sept 10, return on Sept 12.

ASSISTANT: Do you need a business class or a economy class?

USER: I am comfortable with any class.

ASSISTANT: Do you need a connecting flight?

USER: I need a flight with one connection.

ASSISTANT: Do you have any preferences with  timings?

USER: My depart time should be evening.

ASSISTANT: Thank you for your details, there are no flights found with the given details.

USER: No problem, thank you.

ASSISTANT: Thank you.