{
 gROOT->Reset();
 Int_t n = 20;
 Double_t x[n], y[n], x1[n], y1[n];
 // create the blue graph with a cos function
 for (Int_t i=0;i<n;i++) {
   x[i]   = i*0.5;
   y[i]   = 5*cos(x[i]+0.2);
   x1[i] = i*0.5;
   y1[i] = 5*sin(x[i]+0.2);
 }
TH1F *h=new TH1F("h","",10,0,1);
TH1F *g=new TH1F("g","",10,0,1);

h->FillRandom("gaus",100000);
g->FillRandom("gaus", 90000);

/*
 TGraph *gr1 = new TGraph(n,x,y);
 TGraph *gr2 = new TGraph(n,x1,y1);
*/
TGraph *gr1 = new TGraph(h);
TGraph *gr2 = new TGraph(g);
cout << gr2->GetHistogram()->GetMaximum() << endl;

 TCanvas *c1 = new TCanvas ("c1","Two Graphs" , 200,
    10, 600, 400);
 // draw the graph with axis,contineous line, and
 // put a * at each point
 gr1->SetLineColor(4);
 gr1->Draw("AC*");
cout << gr1->GetHistogram()->GetMaximum() << endl;
 // superimpose the second graph by leaving out
 // the axis option "A"
 gr2->SetLineWidth(3);
 gr2->SetMarkerStyle(21);
 gr2->SetLineColor(2);
 gr2->Draw("CP");
}