Okay, so let's look at this system here. This system is composed of two containers connected by a bridge, and within the container, there are four different molecules. And these molecules are allowed to diffuse from one side to the other side. So let's see what's the most probable situation that we can get. Okay, so what's the likelihood that we're going to get four different molecules all on the left side? Well, this thing could only occur one time, or there's one way that this can occur.