So let's say this is r of t right over there. We could say y is equal to r of t. And this is t. And let's see, the first minute goes from zero to one, second minute goes from one to two, third minute goes from two to three, fourth minute goes from three to four. The rate function, this actually just looks like a straight up linear rate function, looks something like this. And so what is the fourth minute? Well the fourth minute is, the first minute is this one, second, third, fourth. The fourth minute is going from minute three to minute four. So what we wanna do is the expression that gives us this area right over here under the rate curve.