diff -r 25d9c3b2bc99 -r c0d9e6548b08 solutions5/bfc.scala
--- a/solutions5/bfc.scala	Sun Aug 23 14:39:58 2020 +0100
+++ b/solutions5/bfc.scala	Tue Aug 25 01:18:17 2020 +0100
@@ -170,14 +170,16 @@
 // that is write(mem, mp, 0). 
 //
 // The easiest way to modify a string in this way is to use the regular
-// expression """[^<>+-.\[\]]""", which recognises everything that is 
+// expression """[^<>+-.\[\]@*#]""", which recognises everything that is 
 // not a bf-command and replace it by the empty string. Similarly the
 // regular expression """\[-\]""" finds all occurences of [-] and 
 // by using the Scala method .replaceAll you can repplace it with the 
 // string "0" standing for the new bf-command.
 
-def optimise(s: String) : String = 
-  s.replaceAll("""[^<>+-.\[\]]""","").replaceAll("""\[-\]""", "0")
+def optimise(s: String) : String = {
+  s.replaceAll("""[^<>+-.\[\]@*#]""","")
+   .replaceAll("""\[-\]""", "0")
+}
 
 
 def compute3(pg: String, tb: Map[Int, Int], pc: Int, mp: Int, mem: Mem) : Mem = {
@@ -208,6 +210,7 @@
 
 // testcases
 
+//println(optimise(load_bff("collatz.bf")))
 //optimise(load_bff("benchmark.bf"))          // should have inserted 0's
 //optimise(load_bff("mandelbrot.bf")).length  // => 11203
  
@@ -291,6 +294,8 @@
 }
 
 // testcases
+//println(combine(optimise(load_bff("collatz.bf"))))
+
 //combine(optimise(load_bff("benchmark.bf"))) // => """>A+B[<A+M>A-A]<A[[....."""
 
 //time_needed(1, run4(load_bff("benchmark.bf")))