float ND_pair(float minT_cut, float maxT_cut)
{

 
//gROOT->ProcessLine(".L ND_integral.C");
  gROOT->Reset();
  gROOT->SetStyle("Plain");
  gStyle->SetPalette(1);
  gStyle->SetOptStat(1110);
  gStyle->SetPadGridX(1);
  gStyle->SetPadGridY(1);  
  gStyle->SetStatY(0.9);
  gStyle->SetStatX(0.9);
  gStyle->SetStatTextColor(1);

  TGaxis::SetMaxDigits(3);

float * upstream_up= new float[2];

//TH2F *TDC2time= new TH2F("TDC2time","Upstream vs event#",1000,0,90,1000,0,200);

if(minT_cut==0 && maxT_cut==0) maxT_cut=100; //no cut

  
  TChain *T = new TChain("ntuple"); 
   
  
        T->Add("r4118.root");
	
	 


 
  char datum[256];
  char selection[256];
  sprintf(datum,"TDC12*0.223:EventNumber/300/60");
  sprintf(selection,"(EventNumber/300/60)>%f && (EventNumber/300/60)<%f && (TDC12*0.223)>0",minT_cut,maxT_cut);
  T->Draw(datum,selection,"goff");




upstream_up[0] = T->GetEntries(selection);


upstream_up[1] = sqrt(upstream_up[0]);

cout<<"number of e+: "<<upstream_up[0]<<"+/-"<<upstream_up[1]<<endl;



return upstream_up;
}