/in/foo.cc: In function 'void dfs(int, int, int)':
/in/foo.cc:47:12: error: reference to 'next' is ambiguous
          i=next[i];
            ^~~~
/in/foo.cc:9:30: note: candidates are: int next [105]
 int n,a[105],sum,minn,u[105],next[105],len,book,s;
                              ^~~~
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:3:
/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:16:8: warning: unused variable 'j' [-Wunused-variable]
  int i,j;
        ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:67:2: error: reference to 'next' is ambiguous
  next[n]=n;
  ^~~~
/in/foo.cc:9:30: note: candidates are: int next [105]
 int n,a[105],sum,minn,u[105],next[105],len,book,s;
                              ^~~~
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:3:
/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:69:26: error: reference to 'next' is ambiguous
         if(a[i]==a[i+1]) next[i]=next[i+1];
                          ^~~~
/in/foo.cc:9:30: note: candidates are: int next [105]
 int n,a[105],sum,minn,u[105],next[105],len,book,s;
                              ^~~~
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:3:
/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:69:34: error: reference to 'next' is ambiguous
         if(a[i]==a[i+1]) next[i]=next[i+1];
                                  ^~~~
/in/foo.cc:9:30: note: candidates are: int next [105]
 int n,a[105],sum,minn,u[105],next[105],len,book,s;
                              ^~~~
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:3:
/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:70:14: error: reference to 'next' is ambiguous
         else next[i]=i;
              ^~~~
/in/foo.cc:9:30: note: candidates are: int next [105]
 int n,a[105],sum,minn,u[105],next[105],len,book,s;
                              ^~~~
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:3:
/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
     ^~~~