That has the effect of putting the y's on the left hand side. And then I can multiply both sides times d x. I can multiply both sides times d x. And we kind of treat, you can treat these differentials as you would treat a variable when you're manipulating it to essentially separate out the variables. And so this will cancel with that. And so we are left with, we are left with y d y, y d y is equal to negative x, and actually let me write it this way. Let me write it as negative x e, actually I might want a little more space. So negative x e to the negative x squared d x.