refactor: remove print

src/sog.cpp

@@ -98,7 +98,6 @@ void SOG::ExportGraphToDotFile(const std::string &filename) const {
     return;
   }
 
-  std::cout << "the graph contains: " << nb_states << " states\n";
   file << "digraph reachab_graph {" << '\n';
 
   // Add the initial node (start point)