example problem : hello world, with java, compiler error

i ask my friends to try a testing contest with Hello world as the question problem. i find that every single "java" code is rejected with message "compiler-error". but no problem when they upload C code. here is the java code : public class hello { public static void main(String[] args) { System.out.println("Hello world!"); } } here is the error message as admin : Compilation unsuccessful Compiling aborted after 1 seconds, compiler output: /usr/sbin/runguard: warning: timelimit exceeded (hard wall time): aborting command /usr/sbin/runguard: warning: command terminated with signal 15 /usr/sbin/runguard: warning: timelimit exceeded (soft wall time)