And now we know what amino acid is found in which one of our containers, so we know which amino acids we have. The next question is, how many of each amino acids do we have in that beaker? So we want to count up those amino acids, and that's exactly what we do in step three. So now that we know the types of amino acids involved, we must determine what the quantity of each one is in our polypeptide. And the way that we're going to do that is use a special type of molecule known as ninhydran. So here we have our five beakers that we basically separated in step two.