/in/foo.cc: In function 'void dfs(int, int, int, int, int)':
/in/foo.cc:23:18: warning: statement has no effect [-Wunused-value]
      used[nx][ny]==1;
      ~~~~~~~~~~~~^~~
/in/foo.cc:39:17: warning: statement has no effect [-Wunused-value]
     used[nx][ny]==1;
     ~~~~~~~~~~~~^~~
/in/foo.cc:54:17: warning: statement has no effect [-Wunused-value]
     used[nx][ny]==1;
     ~~~~~~~~~~~~^~~