#include <iostream>
#include <list>
#include <cstdlib>
#include <boost/multi_index_container.hpp>
#include <boost/multi_index/sequenced_index.hpp>

using namespace std;
using namespace boost;
using namespace boost::multi_index;

class A;
class B;
class A {
public:
#ifdef USE_LIST
    list<B>::iterator b_it;
#else
    multi_index_container<B,indexed_by<sequenced<>>>::iterator b_it;
#endif
    int val;
};
class B {
public:
    list<A>::iterator a_it;
    int val;
};

int main()
{
    list<A> la;
#ifdef USE_LIST
    list<B> lb;
#else
    multi_index_container<B,indexed_by<sequenced<>>> lb;
#endif
    A a;
    a.val = 5;
    B b;
    b.val = 7;
    la.push_front(a);
    lb.push_front(b);
    a = la.front();
    a.b_it = lb.begin();
    cout << a.b_it->val << "\n";

    return EXIT_SUCCESS;
}