TH1D* MakeHistoFromFile(TString filename)
{
   ifstream inp; double x,x1,x2,y;
   inp.open(filename.Data());
   int i = 0;
   while (inp >> x >> y) {
      if (i == 0) x1 = x;
      i++;
   }
   x2 = x;
   inp.close();

   double bw = 1.;  // Bin width
   int    nb = i+1; // Number of bins
   auto h    = new TH1D("h","AIST HPGe Detector Spectrum",nb,x1-bw/2.,x2+bw/2.);
   h->GetXaxis()->SetTitle("Energy (keV)");
   h->GetYaxis()->SetTitle("Count");
   inp.open(filename.Data());
   i = 0;
   while (inp >> x >> y) {
      i++;
      h->SetBinContent(i,y);
   }
   inp.close();
   return h;
}

void File1() {
   auto h = MakeHistoFromFile("File1.txt");
   h->Draw();
}