Code that is both valid C and Java

C.java

//\
public class C { //\
  public static void main(String[] args) { //\
    System.out.println("hello"/*
#include <stdio.h>
int main() {
  {
    return puts("world"/**/);
  }
}

java.c

//\
public class C { //\
  public static void main(String[] args) { //\
    System.out.println("hello"/*
#include <stdio.h>
int main() {
  {
    return puts("world"/**/);
  }
}

$ javac C.java
$ gcc java.c -o java
$ java C && ./java
hello
world