/*
  Inspirado por um exercício do livro

  Ravi Sethi, "Programming Languages: Concepts and Constructs, 2nd
  Edition". Addison Wesley, 1996.
*/

void main()
{
  int a = 0;

  int P()
  {
    int x, y, z;

    int Q()
    {
      int R()
      {
	a = 1;
	z = P();

	return 10 * z;
      }

      y = R();

      return 10 * y;
    }

    if (a == 0)
      {
	x = Q();

	println("x = ", x, ", y = ", y, ", z = ", z);

	return 10 * x;
      }
    else
      return 1;
  }

  println(P());
}