And I'll explain in a little bit why we put one here, one here, one here, and then one here. And not two here and two here and none here. I'll explain why in a second. Now, so I place one here, one here, one here, and then I place my fourth one into my X. So we can also represent this guy in the following way. We simply erase all these X's as ZS and simply say two P and we place a four on top.