/in/foo.cc: In function 'void add(int, int, int)':
/in/foo.cc:15:22: error: reference to 'next' is ambiguous
 to[cnt]=b,val[cnt]=c,next[cnt]=head[a],head[a]=cnt;
                      ^~~~
/in/foo.cc:9:14: note: candidates are: int next [200010]
 int to[maxm],next[maxm],val[maxm],head[maxn],dis[maxn],vis[maxn],d[maxn],p[maxn],q[maxn],f[51][maxn];
              ^~~~
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:2:
/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 work()':
/in/foo.cc:44:25: error: reference to 'next' is ambiguous
   for(i=head[u];i!=-1;i=next[i])
                         ^~~~
/in/foo.cc:9:14: note: candidates are: int next [200010]
 int to[maxm],next[maxm],val[maxm],head[maxn],dis[maxn],vis[maxn],d[maxn],p[maxn],q[maxn],f[51][maxn];
              ^~~~
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:2:
/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:75:25: error: reference to 'next' is ambiguous
   for(j=head[i];j!=-1;j=next[j])
                         ^~~~
/in/foo.cc:9:14: note: candidates are: int next [200010]
 int to[maxm],next[maxm],val[maxm],head[maxn],dis[maxn],vis[maxn],d[maxn],p[maxn],q[maxn],f[51][maxn];
              ^~~~
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:2:
/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:84:25: error: reference to 'next' is ambiguous
   for(i=head[u];i!=-1;i=next[i])
                         ^~~~
/in/foo.cc:9:14: note: candidates are: int next [200010]
 int to[maxm],next[maxm],val[maxm],head[maxn],dis[maxn],vis[maxn],d[maxn],p[maxn],q[maxn],f[51][maxn];
              ^~~~
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:2:
/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:107:34: error: reference to 'next' is ambiguous
     for(u=q[i],j=head[u];j!=-1;j=next[j])
                                  ^~~~
/in/foo.cc:9:14: note: candidates are: int next [200010]
 int to[maxm],next[maxm],val[maxm],head[maxn],dis[maxn],vis[maxn],d[maxn],p[maxn],q[maxn],f[51][maxn];
              ^~~~
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:2:
/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
     ^~~~