/in/foo.cc: In function 'bool fun(std::vector<std::vector<int> >&)':
/in/foo.cc:16:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j<rooms[i].size(); j++)
                   ~^~~~~~~~~~~~~~~~
/in/foo.cc:25:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 1; i<rooms.size(); i++){
                  ~^~~~~~~~~~~~~