#include <boost/mpl/greater_equal.hpp>

#include <boost/mpl/int.hpp>

#include <boost/mpl/eval_if.hpp>

#include <boost/mpl/equal_to.hpp>

#include <boost/mpl/multiplies.hpp>

#include <boost/mpl/prior.hpp>

#include <boost/mpl/placeholders.hpp>

#include <boost/mpl/assert.hpp>

#include <boost/static_assert.hpp>

namespace mpl = boost::mpl;

using namespace mpl::placeholders;

template <int n>

struct FACTORIAL_of_NEGATIVE_NUMBER

: mpl::greater_equal<mpl::int_<n>, mpl::int_<0> >

{};

template <class N>

struct factorial

};

factorial<mpl::int_<0> > x1;

factorial<mpl::int_<-1> > x2;