/in/foo.cc: In member function 'int Date::difference(Date&)':
/in/foo.cc:40:17: error: 'num' was not declared in this scope; did you mean 'enum'?
   40 |                 num+=d.YearDay(year)-d.pass(d.year,d.month,d.day);
      |                 ^~~
      |                 enum