foo.cc: In function 'void dfs(int, int)':
foo.cc:26:22: warning: iteration 7 invokes undefined behavior [-Waggressive-loop-optimizations]
   26 |    dfs(x+dx[i],y+dy[i]);
      |                  ~~~~^
foo.cc:24:16: note: within this loop
   24 |   for(int i=1;i<=8;i++)
      |               ~^~~

[Hydro](https://hydro.ac)提供评测服务