/in/foo.cc: In function 'int main()':
/in/foo.cc:49:9: error: conflicting declaration 'Date d'
  Date d(y,m,d);
         ^
/in/foo.cc:46:9: note: previous declaration as 'int d'
 int y,m,d,num;
         ^
/in/foo.cc:50:4: error: request for member 'Add' in 'd', which is of non-class type 'int'
  d.Add(num);
    ^~~
/in/foo.cc:51:4: error: request for member 'Output' in 'd', which is of non-class type 'int'
  d.Output();
    ^~~~~~