foo.cc: In function ‘void dfs(int, int)’:
foo.cc:30:17: error: too many arguments to function ‘bool check()’
   30 |         if(check(xx,yy)&&a[xx][yy]==0&&!flag[xx][yy])
      |            ~~~~~^~~~~~~
foo.cc:12:6: note: declared here
   12 | bool check()
      |      ^~~~~