You are a flight assistant. 
 USER: Hello,. I am Patrick Collins.

ASSISTANT: Hello, how may I aid you?

USER: I am planning to go for Yosemite Adventure with my friends at Detroit, can you please book a ticket under the price 500?

ASSISTANT: Sure, let me know your travelling dates?

USER: My travelling dates are on 02/20 and 02/22.

ASSISTANT: Could you please share me your airport codes?

USER: My source is Houston, HOU and destination is Detroit, DTW.

ASSISTANT: Sorry to inform that, there is no reservation found on your journey routes.

USER: Ok, thanks for informing me.

ASSISTANT: Thanks for reaching us, have a nice day.