foo.cpp: In function 'void work()':
foo.cpp:44:5: error: reference to 'end' is ambiguous
     end=(1<<m)-1;
     ^
foo.cpp:18:13: note: candidates are: int end
 int n,m,ans,end;
             ^
In file included from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\basic_string.h:42:0,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\string:52,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\locale_classes.h:40,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\ios_base.h:41,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\ios:42,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\ostream:38,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\iostream:39,
                 from foo.cpp:2:
c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\initializer_list:99:5: note:                 template<class _Tp> constexpr const _Tp* std::end(std::initializer_list<_Tp>)
     end(initializer_list<_Tp> __ils) noexcept
     ^
In file included from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\string:51:0,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\locale_classes.h:40,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\ios_base.h:41,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\ios:42,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\ostream:38,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\iostream:39,
                 from foo.cpp:2:
c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\range_access.h:97:5: note:                 template<class _Tp, unsigned int _Nm> _Tp* std::end(_Tp (&)[_Nm])
     end(_Tp (&__arr)[_Nm])
     ^
c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\range_access.h:78:5: note:                 template<class _Container> decltype (__cont.end()) std::end(const _Container&)
     end(const _Container& __cont) -> decltype(__cont.end())
     ^
c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\range_access.h:68:5: note:                 template<class _Container> decltype (__cont.end()) std::end(_Container&)
     end(_Container& __cont) -> decltype(__cont.end())
     ^
foo.cpp:46:17: error: reference to 'end' is ambiguous
  for(int s=0;s<=end;s++) {
                 ^
foo.cpp:18:13: note: candidates are: int end
 int n,m,ans,end;
             ^
In file included from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\basic_string.h:42:0,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\string:52,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\locale_classes.h:40,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\ios_base.h:41,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\ios:42,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\ostream:38,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\iostream:39,
                 from foo.cpp:2:
c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\initializer_list:99:5: note:                 template<class _Tp> constexpr const _Tp* std::end(std::initializer_list<_Tp>)
     end(initializer_list<_Tp> __ils) noexcept
     ^
In file included from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\string:51:0,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\locale_classes.h:40,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\ios_base.h:41,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\ios:42,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\ostream:38,
                 from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\iostream:39,
                 from foo.cpp:2:
c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\range_access.h:97:5: note:                 template<class _Tp, unsigned int _Nm> _Tp* std::end(_Tp (&)[_Nm])
     end(_Tp (&__arr)[_Nm])
     ^
c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\range_access.h:78:5: note:                 template<class _Container> decltype (__cont.en