 Yeah, it's quite interesting. It had all the attributes, right? There's the giant problem. Basically, nobody was working on it. And it seemed tractable to me because it was a chemistry problem. The chemistry problem was most of the CO2 emissions have nothing to do with energy. They have to do with the chemistry of making cement. So can I change the chemistry such that it doesn't make CO2 emissions? And we looked around at the existing solutions and we saw that most folks were working on making a novel material, not Portland cement.