/in/foo.cc: In function 'bool part(std::__cxx11::string&, std::__cxx11::string&)':
/in/foo.cc:24:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0, j = 0; j < b.size(); j++)
                         ~~^~~~~~~~~~
/in/foo.cc:25:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (b[j] == a[i] && ++i == a.size())
                       ~~~~^~~~~~~~~~~