In file included from foo.cpp:1:
    In file included from /usr/include/c++/4.2.1/algorithm:64:
    /usr/include/c++/4.2.1/bits/stl_algobase.h:283:18: error: no viable overloaded
          '='
                  *__result = *__first;
                  ~~~~~~~~~ ^ ~~~~~~~~
    /usr/include/c++/4.2.1/bits/stl_algobase.h:315:14: note: in instantiation of
          function template specialization 'std::__copy<false,
          std::random_access_iterator_tag>::copy<unsigned long *,
          std::back_insert_iterator<std::vector<std::basic_string<char>,
          std::allocator<std::basic_string<char>>>> >' requested here
          return std::__copy<__simple, _Category>::copy(__first, __last, __result);
                 ^
    /usr/include/c++/4.2.1/bits/stl_algobase.h:349:18: note: in instantiation of
          function template specialization 'std::__copy_aux<unsigned long *,
          std::back_insert_iterator<std::vector<std::basic_string<char>,
          std::allocator<std::basic_string<char>>>> >' requested here
            { return std::__copy_aux(__first.base(), __last.base(), __result); }
                     ^
    /usr/include/c++/4.2.1/bits/stl_algobase.h:400:15: note: in instantiation of
          function template specialization 'std::__copy_normal<true,
          false>::__copy_n<__gnu_cxx::__normal_iterator<unsigned long *,
          std::vector<unsigned long, std::allocator<unsigned long>>>,
          std::back_insert_iterator<std::vector<std::basic_string<char>,
          std::allocator<std::basic_string<char>>>> >' requested here
           return std::__copy_normal<__in, __out>::__copy_n(__first, __last,
                  ^
    foo.cpp:12:3: note: in instantiation of function template specialization
          'std::copy<__gnu_cxx::__normal_iterator<unsigned long *,
          std::vector<unsigned long, std::allocator<unsigned long>>>,
          std::back_insert_iterator<std::vector<std::basic_string<char>,
          std::allocator<std::basic_string<char>>>> >' requested here
      std::copy(foo.begin(), foo.end(), std::back_inserter(bar));
      ^
    /usr/include/c++/4.2.1/bits/stl_iterator.h:385:11: note: candidate function (the
          implicit copy assignment operator) not viable: no known conversion from
          'unsigned long' to 'const
          std::back_insert_iterator<std::vector<std::basic_string<char>,
          std::allocator<std::basic_string<char>>>>' for 1st argument;
        class back_insert_iterator
              ^
    /usr/include/c++/4.2.1/bits/stl_iterator.h:411:7: note: candidate function not
          viable: no known conversion from 'unsigned long' to 'const
          std::basic_string<char>' for 1st argument;
          operator=(typename _Container::const_reference __value)
          ^
    1 error generated.