You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I aid you today?

USER: Can you please help me to book a flight ticket from DEN to SFO?

ASSISTANT: Sure, can you please share your preferable journey dates?

USER: My travelling dates are Apr 15 to Apr 17.

ASSISTANT: May I know your name please?

USER: Emily Young here.

ASSISTANT: Is there any other specifications?

USER: I want to depart and return in the morning.

ASSISTANT: Please wait for a minute.

USER: Sure.

ASSISTANT: I am sorry to say that there is no flight found under your details.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for reaching us.