/in/foo.cc: In function 'int Index(std::__cxx11::string, int, std::__cxx11::string)':
/in/foo.cc:12:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  while(i<s.size() && j<t.size())
        ~^~~~~~~~~
/in/foo.cc:12:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  while(i<s.size() && j<t.size())
                      ~^~~~~~~~~
/in/foo.cc:19:6: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if(j==t.size())
     ~^~~~~~~~~~