And this nitrogen essentially came from this step also. Step one, the free ammonium. And so the urea is then transported into the bloodstream, moved into the kidneys and it's removed by the kidneys via urine. Now, if we sum up all these steps, this is the net reaction that we get. So a single carbon dioxide molecule, a single free ammonium to water molecule. So one water molecule came from here and a second water molecule came from transforming the carbon dioxide into bicarbonate.