Int_t empty[60];
TFile f("TGraphs.root");
TIter nextkey(f.GetListOfKeys());
Int_t i = 0;
TKey *key;
void filereader(){
    while ((key = (TKey*)nextkey())) {
    TGraph *g = (TGraph*)f.Get(key->GetName());
    empty[i] = g->GetMarkerColor();
    cout << g->GetMarkerColor() << endl;
    ++i;
    }
}