/in/foo.cc: In function 'int Index(std::__cxx11::string&, int, std::__cxx11::string&)':
/in/foo.cc:7:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = k; i <= s.size() - t.size(); i++)
                     ~~^~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc:10:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int j = 0; j < t.size(); j++)
                         ~~^~~~~~~~~~