How do I check if a player goes out of the window?

The title basically says it all. But if it is possible, is there a way to check which side of the window they went off? Like if they went off the bottom of the screen, it'd trigger an event. and if it goes off the left, nothing happens.

You can use a system like that

What blocks are those? O_o

These are compare blocks. One is

System -> Compare two values

The other one is

System -> Compare variable