/in/foo.cc: In function 'void topsort()':
/in/foo.cc:42:29: error: no matching function for call to 'max(long long int&, int&)'
             ans=max(ans,d[v]);
                             ^
In file included from /usr/include/c++/6/deque:60:0,
                 from /usr/include/c++/6/queue:60,
                 from /in/foo.cc:2:
/usr/include/c++/6/bits/stl_algobase.h:219:5: note: candidate: template<class _Tp> const _Tp& std::max(const _Tp&, const _Tp&)
     max(const _Tp& __a, const _Tp& __b)
     ^~~
/usr/include/c++/6/bits/stl_algobase.h:219:5: note:   template argument deduction/substitution failed:
/in/foo.cc:42:29: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'int')
             ans=max(ans,d[v]);
                             ^
In file included from /usr/include/c++/6/deque:60:0,
                 from /usr/include/c++/6/queue:60,
                 from /in/foo.cc:2:
/usr/include/c++/6/bits/stl_algobase.h:265:5: note: candidate: template<class _Tp, class _Compare> const _Tp& std::max(const _Tp&, const _Tp&, _Compare)
     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
     ^~~
/usr/include/c++/6/bits/stl_algobase.h:265:5: note:   template argument deduction/substitution failed:
/in/foo.cc:42:29: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'int')
             ans=max(ans,d[v]);
                             ^
In file included from /usr/include/c++/6/algorithm:62:0,
                 from /in/foo.cc:3:
/usr/include/c++/6/bits/stl_algo.h:3459:5: note: candidate: template<class _Tp> _Tp std::max(std::initializer_list<_Tp>)
     max(initializer_list<_Tp> __l)
     ^~~
/usr/include/c++/6/bits/stl_algo.h:3459:5: note:   template argument deduction/substitution failed:
/in/foo.cc:42:29: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
             ans=max(ans,d[v]);
                             ^
In file included from /usr/include/c++/6/algorithm:62:0,
                 from /in/foo.cc:3:
/usr/include/c++/6/bits/stl_algo.h:3465:5: note: candidate: template<class _Tp, class _Compare> _Tp std::max(std::initializer_list<_Tp>, _Compare)
     max(initializer_list<_Tp> __l, _Compare __comp)
     ^~~
/usr/include/c++/6/bits/stl_algo.h:3465:5: note:   template argument deduction/substitution failed:
/in/foo.cc:42:29: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
             ans=max(ans,d[v]);
                             ^