#include <set>
 #include <algorithm>
 #include <iostream>
 
 template<class T> 
 struct print : public std::unary_function<T, void>
 {
 print(std::ostream& out) : os(out) {}
 void operator() (T x) { os << x;}
 std::ostream& os;
 };
 
 enum SortOrder { Increasing, Decreasing };
 
 class fCompare
 {
 public:
 fCompare(const SortOrder& o) : m_order(o) {}
 bool operator() (const int a, const int b) const
 {
 if (m_order == Increasing) return a < b;
 else return b < a;
 }
 private:
 const SortOrder& m_order;
 };
 
 int main()
 {
 SortOrder sort_state = Increasing;
 
 fCompare comp_obj(sort_state);
 std::set<int, fCompare> IntSet(comp_obj);
 
 for (int i = 0; i < 5; ++i)
 {
 IntSet.insert(i);
 }
 for_each(IntSet.begin(), IntSet.end(), print<int>(std::cout));
 std::cout << std::endl;
 
 sort_state = Decreasing;
 
 for (int i = 0; i < 5; ++i)
 {
 IntSet.insert(i);
 }
 for_each(IntSet.begin(), IntSet.end(), print<int>(std::cout));
 std::cout << std::endl;
 }