/in/foo.cc: In function 'int main()':
/in/foo.cc:33:18: error: call of overloaded 'max(int&, int&)' is ambiguous
  cout << max(a, b) << endl;
                  ^
/in/foo.cc:16:3: note: candidate: T max(T, T) [with T = int]
 T max(T a, T b)
   ^~~
In file included from /usr/include/c++/6/bits/char_traits.h:39:0,
                 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_algobase.h:219:5: note: candidate: const _Tp& std::max(const _Tp&, const _Tp&) [with _Tp = int]
     max(const _Tp& __a, const _Tp& __b)
     ^~~
/in/foo.cc:34:46: error: call of overloaded 'max(double&, double&)' is ambiguous
  cout << fixed << setprecision(2) << max(c, d)<<endl;
                                              ^
/in/foo.cc:16:3: note: candidate: T max(T, T) [with T = double]
 T max(T a, T b)
   ^~~
In file included from /usr/include/c++/6/bits/char_traits.h:39:0,
                 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_algobase.h:219:5: note: candidate: const _Tp& std::max(const _Tp&, const _Tp&) [with _Tp = double]
     max(const _Tp& __a, const _Tp& __b)
     ^~~