Courtesy and courtesy are always good. In Russia it is special.
I had a case once. I worked in a flower store at night. The exchange give B-g if from five hundred rubles left.
And in the next turn, the body knocks at me in the window, stretches the five-thousand note and polently asks:
Girl, please give me the most beautiful rose!
Sorry, we don’t have a 5,000 exchange.
You are sitting here, fucking?

And indeed.