{
auto f = new TFile("test.root", "recreate");

auto t1 = new TTree("t1", "t1");
int id1 = 0;
t1->Branch("id", &id1, "id/I");
t1->Fill();
t1->Write();

auto t2 = new TTree("t2", "t2");
int id2 = 0;
t2->Branch("id", &id2, "id/I");
t2->Fill();
t2->Write();

id1=1;
t1->Fill();
t1->Write();

id2=1;
t2->Fill();
t2->AddFriend(t1);
t2->Write();

f->Close();

auto f1 = new TFile("test.root", "read");
auto t1_1 = (TTree*)f1->Get("t1");
auto t2_1 = (TTree*)f1->Get("t2");
for(int i=0; i<t2_1->GetEntries(); i++)
{
	t2_1->GetEntry(i);
	//cout << t2_1id << " " << t1_1.id << endl;
}

cout << "Closing" << endl;
f1->Close();
}