void drawpoisson(TString filename="poissonA.root"){
  TFile *filein = new TFile(filename);
  ndecays->SetFillColor(42);
  fteo->SetLineColor(3);
  fteo2->SetLineColor(2);
  ndecays->Draw("b");
  fteo->Draw("csame");
  fteo2->Draw("csame");
  TCanvas *c2 = new TCanvas();
  fteo2->Draw("c");
  TCanvas *c3 = new TCanvas();
  fteo->Draw("c");
}