class ReCurseMe
{
   public static long g(int n)
   {
      if(n == 0)      {return 1;}
      else if(n == 1) {return 3;}
      else if(n == 2) {return 2;}
      else            {return g(n-1) - 2*g(n-2) + 3*g(n-3);}
   }

   public static void main(String[] args)
   {
      int n = Integer.parseInt(args[0]);
      System.out.println("g(" + n + ") = " + g(n));
   }
}