diff --git a/Optimal_transportation_reconstruction_2/examples/Optimal_transportation_reconstruction_2/otr2_simplest_example_with_tolerance.cpp b/Optimal_transportation_reconstruction_2/examples/Optimal_transportation_reconstruction_2/otr2_simplest_example_with_tolerance.cpp
index 404934cf5bc..091552dcc93 100644
--- a/Optimal_transportation_reconstruction_2/examples/Optimal_transportation_reconstruction_2/otr2_simplest_example_with_tolerance.cpp
+++ b/Optimal_transportation_reconstruction_2/examples/Optimal_transportation_reconstruction_2/otr2_simplest_example_with_tolerance.cpp
@@ -17,13 +17,14 @@ typedef CGAL::Optimal_transportation_reconstruction_2<K>    Otr;
 
 int main ()
 {
-  // Generate a set of random points on the boundary of a square.
+  // Generate 100 random points on the boundary of a square.
   std::vector<Point> points;
   CGAL::Random_points_on_square_2<Point> point_generator(1.);
   CGAL::cpp11::copy_n(point_generator, 100, std::back_inserter(points));
 
-  Otr otr(points);
+  Otr otr(points); // no mass given, one unit mass per point assumed
   otr.run_under_wasserstein_tolerance(0.1);
+ 
 
   return 0;
 }