/in/foo.cc: In function 'bool judge(int, int)':
/in/foo.cc:9:17: warning: iteration 3 invokes undefined behavior [-Waggressive-loop-optimizations]
   int x=i+m[k][0],y=j+m[k][1];
           ~~~~~~^
/in/foo.cc:8:15: note: within this loop
  for(int k=1;k<=4;k++){
              ~^~~