foo.cc: In function 'void add(int, int, int)':
foo.cc:21:5: error: reference to 'next' is ambiguous
   21 |     next[num]=first[u];
      |     ^~~~
In file included from /nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/bits/stl_algobase.h:66,
                 from /nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/algorithm:61,
                 from foo.cc:2:
/nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/bits/stl_iterator_base_funcs.h:213:5: note: candidates are: 'template<class _InputIterator> _InputIterator std::next(_InputIterator, typename std::iterator_traits<_Iter>::difference_type)'
  213 |     next(_InputIterator __x, typename
      |     ^~~~
foo.cc:11:21: note:                 'int next [100007]'
   11 | int num,first[MAXN],next[MAXM],arr[MAXM],cost[MAXM];
      |                     ^~~~
foo.cc: In function 'void init()':
foo.cc:31:12: error: reference to 'next' is ambiguous
   31 |     memset(next,0,sizeof(next));
      |            ^~~~
In file included from /nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/bits/stl_algobase.h:66,
                 from /nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/algorithm:61,
                 from foo.cc:2:
/nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/bits/stl_iterator_base_funcs.h:213:5: note: candidates are: 'template<class _InputIterator> _InputIterator std::next(_InputIterator, typename std::iterator_traits<_Iter>::difference_type)'
  213 |     next(_InputIterator __x, typename
      |     ^~~~
foo.cc:11:21: note:                 'int next [100007]'
   11 | int num,first[MAXN],next[MAXM],arr[MAXM],cost[MAXM];
      |                     ^~~~
foo.cc:31:26: error: reference to 'next' is ambiguous
   31 |     memset(next,0,sizeof(next));
      |                          ^~~~
In file included from /nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/bits/stl_algobase.h:66,
                 from /nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/algorithm:61,
                 from foo.cc:2:
/nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/bits/stl_iterator_base_funcs.h:213:5: note: candidates are: 'template<class _InputIterator> _InputIterator std::next(_InputIterator, typename std::iterator_traits<_Iter>::difference_type)'
  213 |     next(_InputIterator __x, typename
      |     ^~~~
foo.cc:11:21: note:                 'int next [100007]'
   11 | int num,first[MAXN],next[MAXM],arr[MAXM],cost[MAXM];
      |                     ^~~~
foo.cc: In function 'bool pan(int)':
foo.cc:51:37: error: reference to 'next' is ambiguous
   51 |         for (int i=first[u];i!=-1;i=next[i])
      |                                     ^~~~
In file included from /nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/bits/stl_algobase.h:66,
                 from /nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/algorithm:61,
                 from foo.cc:2:
/nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/bits/stl_iterator_base_funcs.h:213:5: note: candidates are: 'template<class _InputIterator> _InputIterator std::next(_InputIterator, typename std::iterator_traits<_Iter>::difference_type)'
  213 |     next(_InputIterator __x, typename
      |     ^~~~
foo.cc:11:21: note:                 'int next [100007]'
   11 | int num,first[MAXN],next[MAXM],arr[MAXM],cost[MAXM];
      |                     ^~~~
foo.cc: In function 'void solve(int)':
foo.cc:85:37: error: reference to 'next' is ambiguous
   85 |         for (int i=first[u];i!=-1;i=next[i])
      |                                     ^~~~
In file included from /nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/bits/stl_algobase.h:66,
                 from /nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/algorithm:61,
                 from foo.cc:2:
/nix/store/lwv26rw55rr8k8dc9217ifp5sb0fr9k4-gcc/include/c++/11.3.0/bits/stl_iterator_base_funcs.h:213:5: note: candidates are: 'template<class _InputIterator> _InputIterator std::next(_InputIterator, typename std::iterator_traits<_Iter>::difference_type)'
  213 |     next(_InputIterator __x, typename
      |     ^~~~
foo.cc:11:21: note:                 'int next [100007]'
   11 | int num,first[MAXN],next[MAXM],arr[MAXM],cost[MAXM];
      |                     ^~~~

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