Borderou de evaluare (job #101762)

Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:8:9: error: no match for ‘operator-’ in ‘f - r’ user.cpp:8:9: note: candidates are: /usr/include/c++/4.6/bits/stl_iterator.h:321:5: note: template<class _Iterator> typename std::reverse_iterator::difference_type std::operator-(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&) /usr/include/c++/4.6/bits/stl_iterator.h:373:5: note: template<class _IteratorL, class _IteratorR> decltype ((__y.base() - __x.base())) std::operator-(const std::reverse_iterator<_IteratorL>&, const std::reverse_iterator<_IteratorR>&) /usr/include/c++/4.6/bits/stl_iterator.h:1098:5: note: template<class _IteratorL, class _IteratorR> decltype ((__x.base() - __y.base())) std::operator-(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorR>&) /usr/include/c++/4.6/bits/stl_iterator.h:1105:5: note: template<class _Iterator> decltype ((__x.base() - __y.base())) std::operator-(const std::move_iterator<_Iterator>&, const std::move_iterator<_Iterator>&)