void get_xsec(TFile*, TH1F*, TH1F*);

int nu_xsec()
{
gROOT->Reset();
gStyle->SetOptStat(0000);

Float_t x_nu[21]={1,2,3,4,5,6,7,8,9,10,11,12,14,16,18,20,22,26,30,40,50};

 //Acceptance correction histogram

 TH1F *accep[3];
 TList * accep_list= new TList();
 TH1F *after_accep_corr[3];

 char *histname_accep   = new char[20];
 char *histname_accep_corr   = new char[30];

   //stop,exit,total counter
   for (Int_t k=0; k<3; k++) {

       sprintf(histname_accep, "accep_%d",k+1);
       accep[k] = new TH1F(histname_accep,"",20,x_nu);

       accep_list->Add(accep[k]);

       sprintf(histname_accep_corr, "after_accep_corr_%d",k+1);
       after_accep_corr[k] = new TH1F(histname_accep_corr,"",20,x_nu);
   }

 //Xsec histograms

  TH1F *final_xsec[3][2];
  TList * xsec_list= new TList();

  char *histname_xsec         = new char[30];

   //stop,exit,total counter
   for (Int_t k=0; k<3; k++) {

   //nu<1 and nu<2 counter
     for (Int_t l=0; l<2; l++) {

       sprintf(histname_xsec, "final_xsec_%d_%d",k+1,l+1);
       final_xsec[k][l] = new TH1F(histname_xsec,"",20,x_nu);

       xsec_list->Add(final_xsec[k][l]);
     }
   }


   TFile *f_flux = new TFile("nu_flux_output.root","READ");

   cout<<"\ngetting the xsec(nu<1)\n"<<endl;

   get_xsec(final_flux_1_1,after_accep_corr[0], final_xsec[0][0]);

}


void get_xsec(TFile *flux , TH1F *accep_data , TH1F *xsec ){


}