{
   auto hsurf1 = new TH2F("hsurf1","3D text example ",30,-4,4,30,-20,20);
   float px, py;
   for (Int_t i = 0; i < 25000; i++) {
      gRandom->Rannor(px,py);
      hsurf1->Fill(px-1,5*py);
      hsurf1->Fill(2+0.5*px,2*py-10.,0.1);
   }
   hsurf1->Draw("SURF1");
   int binx,biny,binz;
   int bmax = hsurf1->GetMaximumBin(binx,biny,binz);
   double xm = hsurf1->GetXaxis()->GetBinCenter(binx);
   double ym = hsurf1->GetYaxis()->GetBinCenter(biny);
   double zm = hsurf1->GetMaximum();
   auto t = new TAnnotation(xm,ym,zm,Form("Maximum = %g",zm));
   t->SetTextFont(42);
   t->SetTextSize(0.03);
   t->Draw();
}