{
 gROOT->Reset();


 TTree *tree = new TTree("Tree","An example of a ROOT tree");
 Int_t x, y;

 tree -> Branch("x",&x,"x/I");
 tree -> Branch("y",&y,"y/I");
 
 Int_t n = 1100000;

 for (Int_t i=0;i<n;i++) {
   x = i;
   y = 2*i;
   tree->Fill();
 }
 
 TCanvas c;
 c->Divide(1,2);

 c->cd(1);

 tree->Draw("y:x");
 Graph = (TGraph*)gPad->GetPrimitive("Graph");
 TGraph *g1 = Graph->Clone("g1");


 c->cd(2);
 g1->Draw("AP");

}