/in/foo.cc: In function 'std::vector<short int>& operator++(std::vector<short int>&)':
/in/foo.cc:12:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < self.size(); i++)
                  ~~^~~~~~~~~~~~~
/in/foo.cc: In function 'bool hw(const std::vector<short int>&)':
/in/foo.cc:28:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < (arg.size()>>1); i++)
                  ~~^~~~~~~~~~~~~~~~~