foo.cpp: In function 'int dfs(int, Int64)':
foo.cpp:19:22: error: reference to 'hash' is ambiguous
  Hash::iterator it = hash.find(id);
                      ^
foo.cpp:14:6: note: candidates are: Hash hash
 Hash hash;
      ^
In file included from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\basic_string.h:3033:0,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\string:52,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\random:41,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_algo.h:65,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\algorithm:62,
                 from foo.cpp:1:
c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\functional_hash.h:58:12: note:                 template<class _Tp> struct std::hash
     struct hash;
            ^
foo.cpp:20:12: error: reference to 'hash' is ambiguous
  if (it != hash.end()) return it->second;
            ^
foo.cpp:14:6: note: candidates are: Hash hash
 Hash hash;
      ^
In file included from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\basic_string.h:3033:0,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\string:52,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\random:41,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_algo.h:65,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\algorithm:62,
                 from foo.cpp:1:
c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\functional_hash.h:58:12: note:                 template<class _Tp> struct std::hash
     struct hash;
            ^
foo.cpp:29:9: error: reference to 'hash' is ambiguous
  return hash[id] = now;
         ^
foo.cpp:14:6: note: candidates are: Hash hash
 Hash hash;
      ^
In file included from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\basic_string.h:3033:0,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\string:52,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\random:41,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_algo.h:65,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\algorithm:62,
                 from foo.cpp:1:
c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\functional_hash.h:58:12: note:                 template<class _Tp> struct std::hash
     struct hash;
            ^
foo.cpp: In function 'void dfs(int, int, int)':
foo.cpp:78:47: error: reference to 'ref' is ambiguous
   for (int i = 1; i <= M; ++i) if (!e[i].del) ref[e[i].u] = ref[e[i].v] = 1;
                                               ^
foo.cpp:68:24: note: candidates are: int ref [55]
 int deg[55], prec[55], ref[55], fa[55];
                        ^
In file included from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_algo.h:66:0,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\algorithm:62,
                 from foo.cpp:1:
c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\functional:493:5: note:                 template<class _Tp> std::reference_wrapper<_Tp> std::ref(std::reference_wrapper<_Tp>)
     ref(reference_wrapper<_Tp> __t) noexcept
     ^
c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\functional:485:10: note:                 template<class _Tp> void std::ref(const _Tp&&)
     void ref(const _Tp&&) = delete;
          ^
c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\functional:475:5: note:                 template<class _Tp> std::reference_wrapper<_Tp> std::ref(_Tp&)
     ref(_Tp& __t) noexcept
     ^
foo.cpp:78:61: error: reference to 'ref' is ambiguous
   for (int i = 1; i <= M; ++i) if (!e[i].del) ref[e[i].u] = ref[e[i].v] = 1;
                                                             ^
foo.cpp:68:24: note: candidates are: int ref [55]
 int deg[55], prec[55], ref[55], fa[55];
                        ^
In file included from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_algo.h:66:0,