/in/foo.cc: In function 'void down(int, int)':
/in/foo.cc:27:5: warning: unused variable 'x' [-Wunused-variable]
   27 | int x=(k-1)/5+1,y=(k-1)%5+1;
      |     ^
/in/foo.cc:27:17: warning: unused variable 'y' [-Wunused-variable]
   27 | int x=(k-1)/5+1,y=(k-1)%5+1;
      |                 ^