public class Fibonacci{

    public static long F(long n){

        System.out.println("call F" + n);

        if (n == ) return ;

        if (n == ) return ;

        long t = F(n-) + F (n-);

        System.out.println("return " + t);

        return t;

    }

    public static void main(String[] args)

    {

        long N = Long.parseLong(args[]);

        System.out.println(N+"th Fibonacci number is " + F(N));

    }

}

java Fibonacci 4

call F4

call F3

call F2

call F1

call F0

return 1

call F1

return 2

call F2

call F1

call F0

return 1

return 3

4th Fibonacci number is 3