Fix 2004/kopczynski and format fix README.md

The fix is that we cannot pass -ON to the compiler. With -ON it enters
an infinite loop as the variable l goes up, not down.

Format fix README.md.

Add kopczynski-a to show what happens when it's not a number.

2004/kopczynski/kopczynski-a

@@ -0,0 +1,8 @@
+      ####
+     ######
+    ##    ##
+   ###    ###
+   ##########
+   ##      ##
+   ##      ##
+