/in/foo.cc: In function 'void work(int, int)':
/in/foo.cc:32:12: error: reference to 'next' is ambiguous
     memset(next,0,sizeof(next));
            ^~~~
/in/foo.cc:12:55: note: candidates are: int next [2003]
 int up[N][N],down[N][N],le[N][N],ri[N][N],del[N],b[N],next[N],tot;
                                                       ^~~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:66:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator_base_funcs.h:205:5: note:                 template<class _ForwardIterator> _ForwardIterator std::next(_ForwardIterator, typename std::iterator_traits<_Iter>::difference_type)
     next(_ForwardIterator __x, typename
     ^~~~
/in/foo.cc:32:26: error: reference to 'next' is ambiguous
     memset(next,0,sizeof(next));
                          ^~~~
/in/foo.cc:12:55: note: candidates are: int next [2003]
 int up[N][N],down[N][N],le[N][N],ri[N][N],del[N],b[N],next[N],tot;
                                                       ^~~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:66:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator_base_funcs.h:205:5: note:                 template<class _ForwardIterator> _ForwardIterator std::next(_ForwardIterator, typename std::iterator_traits<_Iter>::difference_type)
     next(_ForwardIterator __x, typename
     ^~~~
/in/foo.cc:36:28: error: reference to 'next' is ambiguous
         for(int k=b[x];k;k=next[k])add(del[k],-1);
                            ^~~~
/in/foo.cc:12:55: note: candidates are: int next [2003]
 int up[N][N],down[N][N],le[N][N],ri[N][N],del[N],b[N],next[N],tot;
                                                       ^~~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:66:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator_base_funcs.h:205:5: note:                 template<class _ForwardIterator> _ForwardIterator std::next(_ForwardIterator, typename std::iterator_traits<_Iter>::difference_type)
     next(_ForwardIterator __x, typename
     ^~~~
/in/foo.cc:59:9: error: reference to 'next' is ambiguous
         next[tot]=b[x+len];
         ^~~~
/in/foo.cc:12:55: note: candidates are: int next [2003]
 int up[N][N],down[N][N],le[N][N],ri[N][N],del[N],b[N],next[N],tot;
                                                       ^~~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:66:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator_base_funcs.h:205:5: note:                 template<class _ForwardIterator> _ForwardIterator std::next(_ForwardIterator, typename std::iterator_traits<_Iter>::difference_type)
     next(_ForwardIterator __x, typename
     ^~~~
/in/foo.cc: In function 'void work1(int, int)':
/in/foo.cc:72:12: error: reference to 'next' is ambiguous
     memset(next,0,sizeof(next));
            ^~~~
/in/foo.cc:12:55: note: candidates are: int next [2003]
 int up[N][N],down[N][N],le[N][N],ri[N][N],del[N],b[N],next[N],tot;
                                                       ^~~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:66:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator_base_funcs.h:205:5: note:                 template<class _ForwardIterator> _ForwardIterator std::next(_ForwardIterator, typename std::iterator_traits<_Iter>::difference_type)
     next(_ForwardIterator __x, typename
     ^~~~
/in/foo.cc:72:26: error: reference to 'next' is ambiguous
     memset(next,0,sizeof(next));
                          ^~~~
/in/foo.cc:12:55: note: candidates are: int next [2003]
 int up[N][N],down[N][N],le[N][N],ri[N][N],del[N],b[N],next[N],tot;
                                                       ^~~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:66:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator_base_funcs.h:205:5: note:                 template<class _ForwardIterator> _ForwardIterator std::next(_ForwardIterator, typename std::iterator_traits<_Iter>::difference_type)
     next(_ForwardIterator __x, typename
     ^~~~
/in/foo.cc:76:28: error: reference to 'next' is ambiguous
         for(int k=b[x];k;k=next[k])add(del[k],-1);
                            ^~~~
/in/foo.cc:12:55: note: candidates are: int next [2003]
 int up[N][N],down[N][N],le[N][N],ri[N][N],del[N],b[N],next[N],tot;
                                                       ^~~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:66:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator_base_funcs.h:205:5: note:                 template<class _ForwardIterator> _ForwardIterator std::next(_ForwardIterator, typename std::iterator_traits<_Iter>::difference_type)
     next(_ForwardIterator __x, typename
     ^~~~
/in/foo.cc:99:9: error: reference to 'next' is ambiguous
         next[tot]=b[x-len-1];
         ^~~~
/in/foo.cc:12:55: note: candidates are: int next [2003]
 int up[N][N],down[N][N],le[N][N],ri[N][N],del[N],b[N],next[N],tot;
                                                       ^~~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:66:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator_base_funcs.h:205:5: note:                 template<class _ForwardIterator> _ForwardIterator std::next(_ForwardIterator, typename std::iterator_traits<_Iter>::difference_type)
     next(_ForwardIterator __x, typename
     ^~~~