diff --git a/scala/dA.scala b/scala/dA.scala
index c66b7e9..b9a658c 100644
--- a/scala/dA.scala
+++ b/scala/dA.scala
@@ -1,3 +1,6 @@
+// $ scalac dA.scala
+// $ scala dA
+
 import scala.util.Random
 import scala.math