template <typename Iterator>
bool next_combination(const Iterator first, Iterator k, const Iterator last){
	if ((first == last) || (first == k) || (last == k))
		return false;
	Iterator i1 = first;
	Iterator i2 = last;
	++i1;
	if (last == i1)
		return false;
	i1 = last;
	--i1;
	i1 = k;
	--i2;
	while (first != i1){
      	if (*--i1 < *i2){
        	Iterator j = k;
         	while (!(*i1 < *j)) ++j;
         	std::iter_swap(i1,j);
         	++i1;
         	++j;
         	i2 = k;
         	std::rotate(i1,j,last);
        	while (last != j){
           		++j;
            	++i2;
        	}
        std::rotate(k,i2,last);
        return true;
      	}
   	}
   std::rotate(first,k,last);
   return false;
}

auto DrawT(TTree *const tree, const std::vector<size_t>& nEnts){	
	auto TC = new TCanvas();
	TC->Divide(2, 2);
	int colorInd = 0;
	size_t tcInd = 0;
	auto trd = tree->CloneTree();
	auto cBr = trd->Branch("color", &colorInd, "color/i");
	std::vector<const char*> nameV;
	for(auto branch: *(tree->GetListOfBranches()))	
		nameV.push_back(branch->GetName());
	for(size_t nEnt: nEnts){
		for(size_t i = 0; i != nEnt; ++i)
			cBr->Fill();
		++colorInd;
	}
	trd->SetMarkerStyle(8);
	std::vector<std::string> nmEvec;
	do{
		std::stringstream ss;
		ss<<nameV[0]<<':'<<nameV[1]<<':'<<nameV[2]<<':'<<"color";
		nmEvec.push_back(ss.str());
	}while(next_combination(nameV.begin(), nameV.begin()+3, nameV.end()));
	for(auto ns: nmEvec){
		TC->cd(++tcInd);
		trd->Draw(ns.c_str(), "1");
	}
	return TC;
}
int rep(){
    TF1* tt = new TF1("x", "x", 0, 1);
    tt->Draw();
    auto tDat = new TTree("train","data from csv file");
    tDat->ReadFile("iris_train.txt", "var0/D:var1/D:var2/D:var3/D", ',');
    auto cdr = DrawT(tDat, {40, 40, 40});
    return 0;
}