So water is going to travel in and out and so will the molecules. So eventually, according to what entropy tells us, we're going to want to go from system C to system D. That is, we want to travel from this system to this even system in which we have five molecules on this side on the inside and five molecules on the outside. Now let's look at a third system. Let's look at system E. Now, in system E, we basically have the same system as above, except now our hole is filled in. So we have a continuous circular membrane. So now we can't talk about the side molecules going in and out because side molecules can't go in and out.