This is a simple program, compiled with Sun's javac, no optimisation. Here is the original Java source code:
import java.lang.*;

class Fibo {
	 private static int fib (int x) {
		  if (x > 1)
				return (fib(x - 1) + fib(x - 2));
		  else return (x);
	 }

	 public static void main(String args[]) throws Exception {
	 int number = 0, value;

		  try {
				number = Integer.parseInt(args[0]);
		  } catch (Exception e) {
				System.out.println ("Input error");
				System.exit (1);
		  }
		  value = fib(number);
		  System.out.println ("fibonacci(" + number + ") = " + value);
	 }

}
You use the program like this:
% java Fibo 10
fibonacci(10) = 55
% java Fibo abc
Input error
%
The corresponding C# source code (for .NET decompiler tests) is in DecompilerFiboDotNetSource. -- Main.MikeVanEmmerik - 13 Feb 2003