/opt/scala/bin/scalac: line 50: /dev/null: Permission denied
Main.scala:14: error: type mismatch;
found : Main.a.Node
required: Main.b.Node
b.insertNode(n) // type error
^
one error found
spoj: The program compiled successfully, but Main.class was not found.
Class Main should contain method: def main(args: Array[String]).