Following in the footsteps of the Galaxy Note 3, the Samsung Galaxy S4 (I9500) is making the jump to Android 5.0 Lollipop in Russia. The update weighs in at a hefty 1.05GB and has restrictions for the internal storage.
First off, you'll need around 3GB to complete the update, so you may need to move some stuff off to the microSD card or to a computer. And you may not be able to get all of it back either.
After the install completes it will permanently eat 950MB of the storage. This is due to the new runtime, called ART. It compiles your apps the first time you boot your phone and stores the result, which where those 950MB go. Dalvik had an app cache too, but that was smaller.
So, if you're in Russia and have a Galaxy S4 - the Exynos one - you can check for updates from the settings menu.