{
   auto c16 = new TCanvas("c16","c16",600,400);
   gStyle->SetOptStat(kFALSE);
   auto h3box = new TH3F("h3box","Option BOX",15,-2,2,15,-2,2,15,0,4);
   double x, y, z;
   for (Int_t i=0;i<10000;i++) {
      gRandom->Rannor(x, y);
      z = x*x + y*y;
      h3box->Fill(x,y,z);
   }
   h3box->Draw("BOX");
}