If the currency is in your possession, its (even intentional) damage is not in itself a criminal offense. The change could be criminal, ie probably not painting Palacký's tentacles, but perhaps painting zero at the end. So it's a fact that I was struck by the fact that I owned the currency, I thought they were owned by the state and only in my possession (then it could be a deliberate damage to state property) but I don't wish so.