foo.cpp: In function 'int main()':
foo.cpp:5:8: error: ambiguous overload for 'operator>>' (operand types are 'std::istream {aka std::basic_istream<char>}' and 'int')
     cin>>0;
        ^
foo.cpp:5:8: note: candidates are:
In file included from c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\iostream:40:0,
                 from foo.cpp:1:
c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\istream:120:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__istream_type& (*)(std::basic_istream<_CharT, _Traits>::__istream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
       operator>>(__istream_type& (*__pf)(__istream_type&))
       ^
c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\istream:124:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__ios_type& (*)(std::basic_istream<_CharT, _Traits>::__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>; std::basic_istream<_CharT, _Traits>::__ios_type = std::basic_ios<char>]
       operator>>(__ios_type& (*__pf)(__ios_type&))
       ^
c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\istream:131:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::ios_base& (*)(std::ios_base&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
       operator>>(ios_base& (*__pf)(ios_base&))
       ^
c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\istream:259:7: note: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__streambuf_type*) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>]
       operator>>(__streambuf_type* __sb);
       ^
c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\istream:774:5: note: std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, unsigned char*) [with _Traits = std::char_traits<char>]
     operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
     ^
c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\istream:779:5: note: std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char*) [with _Traits = std::char_traits<char>]
     operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
     ^