/in/foo.cc: In member function 'void Date::Diff(int)':
/in/foo.cc:14:17: error: 'months' was not declared in this scope; did you mean 'month'?
   14 |                 months[12]={0,31,28+isLeap(year),31,30,31,30,31,31,30,31,30,31};
      |                 ^~~~~~
      |                 month
/in/foo.cc: In function 'int main()':
/in/foo.cc:42:10: error: no match for call to '(Date) (int&, int&, int&)'
   42 |         d(year,month,day);
      |         ~^~~~~~~~~~~~~~~~