You are a flight assistant. 
 USER: Hello. This is Alexander White.

ASSISTANT: Hello, how can I help you?

USER: The Denver art museum is one of the largest art museums between the West Coast and Chicago. I would like to go and explore it. Can you please book a flight ticket for me?

ASSISTANT: Sure, please share me your travelling dates?

USER: I will start on 05/19 and return on 05/21.

ASSISTANT: Kindly assign me your airport codes?

USER: I will travel from IAD to DEN.

ASSISTANT: Please wait a minute.

USER: Kindly look for a direct flight .

ASSISTANT: Sorry, there is no direct flights with your given details.

USER: No problem. Thank you for checking it.

ASSISTANT: Thank you for reaching us.