--- a/progs/pow.scala	Thu Sep 26 14:19:23 2019 +0100
+++ b/progs/pow.scala	Mon Sep 30 12:27:15 2019 +0100
@@ -12,7 +12,7 @@
 val B = Set("a", "b", "c", "")
 pow(B, 4)
 pow(B, 4).size                            // -> 121
-
+pow(B, 3).size 
 
 
 val B2 = Set("a", "b", "c", "")