diff --git a/sample/main.cc b/sample/main.cc
index 4aec86f..06a22bb 100644
--- a/sample/main.cc
+++ b/sample/main.cc
@@ -218,7 +218,7 @@ int main(int argc, char** argv)
     cout << "Hello, Bayesian Networks!" << endl;
     showNodesInfo(network, className);
     showCPDS(network);
-    //cout << "Score: " << network.score(Xd, y) << endl;
+    cout << "Score: " << network.score(Xd, y) << endl;
     cout << "PyTorch version: " << TORCH_VERSION << endl;
     return 0;
 }
\ No newline at end of file
diff --git a/src/Factor.cc b/src/Factor.cc
index 4af43d9..247d9ec 100644
--- a/src/Factor.cc
+++ b/src/Factor.cc
@@ -63,21 +63,23 @@ namespace bayesnet {
         torch::Tensor newValues = values.sum(0);
         return new Factor(newVariables, newCardinalities, newValues);
     }
-    Factor* Factor::product(vector<Factor>& factors)
+    Factor* Factor::product(vector<Factor*>& factors)
     {
         vector<string> newVariables;
         vector<int> newCardinalities;
         for (auto factor : factors) {
-            for (auto variable : factor.getVariables()) {
+            vector<string> variables = factor->getVariables();
+            for (auto idx = 0; idx < variables.size(); ++idx) {
+                string variable = variables[idx];
                 if (find(newVariables.begin(), newVariables.end(), variable) == newVariables.end()) {
                     newVariables.push_back(variable);
-                    newCardinalities.push_back(factor.getCardinalities()[factor.getVariables().index(variable)]);
+                    newCardinalities.push_back(factor->getCardinalities()[idx]);
                 }
             }
         }
-        torch::Tensor newValues = factors[0].getValues();
+        torch::Tensor newValues = factors[0]->getValues();
         for (int i = 1; i < factors.size(); i++) {
-            newValues = newValues.matmul(factors[i].getValues());
+            newValues = newValues.matmul(factors[i]->getValues());
         }
         return new Factor(newVariables, newCardinalities, newValues);
     }
diff --git a/src/Factor.h b/src/Factor.h
index c4fee52..f98dc48 100644
--- a/src/Factor.h
+++ b/src/Factor.h
@@ -23,7 +23,7 @@ namespace bayesnet {
         vector<int>& getCardinalities();
         bool contains(string&);
         torch::Tensor& getValues();
-        static Factor* product(vector<Factor>&);
+        static Factor* product(vector<Factor*>&);
         Factor* sumOut(string&);
 
     };