foo.cc: In function 'int dfs(int, int)':
foo.cc:35:1: warning: no return statement in function returning non-void [-Wreturn-type]
   35 | }
      | ^
foo.cc:24:5: warning: infinite recursion detected [-Winfinite-recursion]
   24 | int dfs(int x,int y)
      |     ^~~
foo.cc:33:20: note: recursive call
   33 |                 dfs(nx,ny);
      |                 ~~~^~~~~~~

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