foo.cpp: In function 'int main()':
foo.cpp:6:2: error: 'longlong' was not declared in this scope
  longlong m;
  ^~~~~~~~
foo.cpp:7:5: error: 'm' was not declared in this scope
     m=x*3;
     ^
foo.cpp:8:8: error: no match for 'operator>>' (operand types are 'std::basic_istream<char>::__istream_type {aka std::basic_istream<char>}' and 'const char [3]')
  cin>>x>>"/n";
  ~~~~~~^~~~~~
In file included from C:/mingw32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/iostream:40:0,
                 from foo.cpp:1:
C:/mingw32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/istream:168:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(bool&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
       operator>>(bool& __n)
       ^~~~~~~~
C:/mingw32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/istream:168:7: note:   conversion of argument 1 would be ill-formed:
foo.cpp:8:10: error: invalid initialization of non-const reference of type 'bool&' from an rvalue of type 'bool'
  cin>>x>>"/n";
          ^~~~
In file included from C:/mingw32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/iostream:40:0,
                 from foo.cpp:1:
C:/mingw32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/istream:172:7: note: candidate: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(short int&) [with _CharT = char; _Traits = std::char_traits<char>] <near match>
       operator>>(short& __n);
       ^~~~~~~~
C:/mingw32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/istream:172:7: note:   conversion of argument 1 would be ill-formed:
foo.cpp:8:10: error: invalid conversion from 'const char*' to 'short int' [-fpermissive]
  cin>>x>>"/n";
          ^~~~
foo.cpp:8:10: error: cannot bind rvalue '(short int)((const char*)"/n")' to 'short int&'
In file included from C:/mingw32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/iostream:40:0,
                 from foo.cpp:1:
C:/mingw32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/istream:175:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(short unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
       operator>>(unsigned short& __n)
       ^~~~~~~~
C:/mingw32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/istream:175:7: note:   conversion of argument 1 would be ill-formed:
foo.cpp:8:10: error: invalid conversion from 'const char*' to 'short unsigned int' [-fpermissive]
  cin>>x>>"/n";
          ^~~~
foo.cpp:8:10: error: cannot bind rvalue '(short unsigned int)((const char*)"/n")' to 'short unsigned int&'
In file included from C:/mingw32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/iostream:40:0,
                 from foo.cpp:1:
C:/mingw32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/istream:179:7: note: candidate: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(int&) [with _CharT = char; _Traits = std::char_traits<char>] <near match>
       operator>>(int& __n);
       ^~~~~~~~
C:/mingw32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/istream:179:7: note:   conversion of argument 1 would be ill-formed:
foo.cpp:8:10: error: invalid conversion from 'const char*' to 'int' [-fpermissive]
  cin>>x>>"/n";
          ^~~~
foo.cpp:8:10: error: cannot bind rvalue '(int)((const char*)"/n")' to 'int&'
In file included from C:/mingw32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/iostream:40:0,
                 from foo.cpp:1:
C:/mingw32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/istream:182:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
       operator>>(unsigned i