{
  ifstream infile("my_data.txt"); // Input data file
  TH1F *h1 = new TH1F("h1", "Spectra", 200, 0, 20);
  // for(int i=0; i<3000; ++i) {
  for(int i=0 ; ; ++i) {
    double a;
    infile >> a;
    if ( infile.eof() ) break; // break if End Of File is reached
    h1->Fill(a);
  }
  c1=new TCanvas("c1", "Spectra", 600, 400);
  c1->cd();
  h1->Draw();
}