You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Matthew Garcia here.

ASSISTANT: How can I assist you today?

USER: Actually, I am looking for a direct flight because of emergency in my travel location. So can you please help me out with booking of a flight ticket?

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

USER: I am heading from my location on 12/18 and please book a return ticket on 12/20.

ASSISTANT: Could you please provide the airport codes?

USER: Sure, I want to travel from LGA to SFO.

ASSISTANT: Ok, let me check for the availability of flight on this route.

USER: Sure, take your time.

ASSISTANT: Matthew, I am sorry to inform you that there is no flight available at your request.

USER: Oh! So sad to hear. Anyway, I will choose another alternative to go there. Thank you for the information.

ASSISTANT: Thank you for contacting us.

USER: Welcome.