necessary conditions does necessary conditions could be many. I'm telling you that you don't need more than these three. I can come up with many necessary conditions. It may not still satisfy all. And see, there's the reason I think, see, which one is the reason I think I want to get away from this necessary and sufficient, as we mentioned, this really came from a very structure discipline called geometry. So I'm trying to solve a geometric problem. Now I want to apply to my messy transboundary water management problem. That's the reason I want to make the distinction because here if you look at the news and look at writings you see that yeah this was not a necessary condition. We did not satisfy necessary condition. Then you ask them okay so what are the necessary conditions? So to give you a simple example, I tell you that I want to go from here to New York. So what are the necessary and sufficient conditions? Can you exhaustively write this? No, there would be thousands