#include <TROOT.h>
#include <TChain.h>
#include <TCanvas.h>

#include <sstream>
#include <iostream>

TCanvas c1;
TChain ch("beam", "");
std::stringstream filename;
void caten() {
   for (int i=0; i < 100; ++i) {
      filename.str("");
      filename << "beamtree_" << i << "a.root";
      ch.Add(filename.str().c_str());
      filename.str("");
      filename << "beamtree_" << i << "b.root";
      ch.Add(filename.str().c_str());
      filename.str("");
      filename << "beamtree_" << i << "c.root";
      ch.Add(filename.str().c_str());
      filename.str("");
      filename << "beamtree_" << i << "d.root";
      ch.Add(filename.str().c_str());
   }
   std::cout << "found " << ch.GetListOfFiles()->GetEntries()
             << " root files" << std::endl;
}