/in/foo.cc: In function 'int main()':
/in/foo.cc:14:9: warning: variable 'y1' set but not used [-Wunused-but-set-variable]
   14 |     int y1, m1, d1, y2, m2, d2;
      |         ^~
/in/foo.cc:14:21: warning: variable 'y2' set but not used [-Wunused-but-set-variable]
   14 |     int y1, m1, d1, y2, m2, d2;
      |                     ^~