#include <TROOT.h>
#include <TH1.h>
#include <TH2.h>
#include "TCanvas.h"
#include "TStyle.h"
#include "TH1.h"
#include "TGaxis.h"
#include "TRandom.h"
#include "TObject.h"
#include "TPoint.h"
#include <TSystem.h>
#include <TGraph.h>
#include <TLorentzVector.h>
#include <TGraphAsymmErrors.h>
#include <vector>
#include <iostream>
#include <algorithm>
#include <iomanip>

#include "TMath.h"

using namespace std;
#include <TFile.h>
#include "TH1.h"
#include <math.h>
#include "TMath.h"
#include <map>
#include "TBranch.h"
#include "TBasket.h"

 void savewmass() {
   gStyle->SetOptStat(1001); 
  TCanvas* c1 = new TCanvas("wmass","w-mass",50,50,800,600);

  TFile *f1 = new TFile("WW.root");
  TFile *f2 = new TFile("TT.root");
  TFile *f3 = new TFile("DY.root");


  TH1F *h1 = (TH1F*)f1->Get("W_Tran_mass");
  h1->SetFillColor(6); 
  
  TH1F *h2 = (TH1F*)f2->Get("W_Tran_mass");
  h2->SetFillColor(4);
 
 TH1F *h3 = (TH1F*)f3->Get("W_Tran_mass");
  h3->SetFillColor(3);
 
  THStack* hs= new THStack("hs","W-Mass stacked histograms");

  c1->cd(1);
hs->Add(h1);
hs->Add(h2);
hs->Add(h3);
hs->GetXaxis()->SetTitle("GeV");
hs->GetYaxis()->SetTitle("# of entries");

 hs->Draw();

TLegend *leg = new TLegend(0.6,0.8,0.9,0.9);
 
leg->AddEntry(h1,"WW","f");
leg->AddEntry(h2,"TT","f");
leg->AddEntry(h3,"DY","f");
leg->Draw();

}