void trend(){
  double event_block[100];
  double me[100],se[100],mf[100],sf[100];
  int num=0;
  ifstream in("m.dat");
  while (!in.eof()){
    in >> me[num];
    in >> se[num];
    in >> mf[num];
    in >> sf[num];
    event_block[num]=num+1;
    num++;
  }
 
  int nmax=num-1;
  TGraph *g1=new TGraph(nmax,event_block,me);
  g1->SetMarkerStyle(20);
  g1->SetMarkerColor(2);
  TGraph *g2=new TGraph(nmax,event_block,se);
  g2->SetMarkerStyle(20);
  g2->SetMarkerColor(2);
  TGraph *g3=new TGraph(nmax,event_block,mf);
  g3->SetMarkerStyle(22);
  TGraph *g4=new TGraph(nmax,event_block,sf);
  g4->SetMarkerStyle(22);

  
  TCanvas *canvas=new TCanvas("c1","Mean and resolution",1200,700);
  canvas->Divide(2,1);
  canvas->cd(1);
  TH2F *h=new TH2F("h",";event block;mean [MeV]",num+1,0,num,100,120,134);
  h->Draw();
  g1->Draw("same,p");
  g3->Draw("same,p");

  TLegend *leg1=new TLegend(0.35,0.15,0.65,0.3);
  leg1->AddEntry(g1,"ECAL","p");
  leg1->AddEntry(g3,"FCAL","p");
  leg1->Draw();
 
  canvas->cd(2);
  TH2F *h2=new TH2F("h2",";event block;#sigma [MeV]",num+1,0,num,100,0,12);
  h2->Draw();
  g2->Draw("same,p");
  g4->Draw("same,p");

  TLegend *leg2=new TLegend(0.35,0.15,0.65,0.3);
  leg2->AddEntry(g2,"ECAL","p");
  leg2->AddEntry(g4,"FCAL","p");
  leg2->Draw();
 
}