/in/foo.cc: In function 'int bfs()':
/in/foo.cc:15:39: warning: unused variable 'j' [-Wunused-variable]
  int head=0, tail=1, x, y, nx, ny, i, j, turn, d;
                                       ^
/in/foo.cc:52:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^