fix: output of the observable transitions

app/main.cpp

@@ -67,7 +67,7 @@ void SaveObservablePaths(const std::vector<std::vector<std::string>>& obs_paths,
       line += "path #" + std::to_string(path_id) + ": " +
               std::to_string(obs_p.size()) + " transitions: ";
       for (const auto& t_label : obs_p) {
-        line += t_label + '_';
+        line += "@" + t_label + '@';
       }
       path_id++;