Suppose I am an owner of an SPBU (fuel station). The government and DPR (parliament) has decided to not adjust the price of "premium" (subsidized fuel), but let the price of "pertamax" (non-subsidized fuel) free. What would I do? Well, because the price gap is too yummy not to take advantage of, I'll sell less premium and more pertamax. So be prepared that you'll often find "sorry premium is out of stock"-sign on my gas station. I know that my location is strategic and many of you coming here to buy premium will have no choice except to buy my pertamax. Sorry. And ow, I see a long line now; I can even increase the price! (Actually if I can even be more evil: I would mix the two types of the fuel underground and sell them both under the name "pertamax" on the nozzle - how many of you would check my tanks?).
Did I forget to thank the DPR and protesters?