You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: I am Emma Nelson want to visit BOS, can you book a ticket from DEN?

ASSISTANT: Sure, may I know your respective dates of journey please?

USER: Sure, my travelling dates will be 02/19 and 02/21.

ASSISTANT: Sorry Emma, there is no flight found as per your travelling details.

USER: Ok, no issues. Thank you for checking.

ASSISTANT: You are welcome always.