/in/foo.cc: In function 'bool check(int, int)':
/in/foo.cc:29:9: warning: unused variable 'ax' [-Wunused-variable]
   29 |     int ax = frx[x][y], ay = fry[x][y];
      |         ^~
/in/foo.cc:30:25: warning: unused variable 'by' [-Wunused-variable]
   30 |     int bx = fcx[x][y], by = fcy[x][y];
      |                         ^~