{
   auto c1 = new TCanvas("c1","c1",600,400);
   auto he = new TH1F("he","Distribution drawn with error bars (option E1)  ",100,-3,3);
   for (int i=0; i<10000; i++) he->Fill(gRandom->Gaus(0,1));
   gStyle->SetEndErrorSize(3);
   gStyle->SetErrorX(1.);
   he->SetMarkerStyle(20);
   he->Draw("E1");
}