/in/foo.cc: In function 'Result Match(std::__cxx11::string&)':
/in/foo.cc:15:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < s.length(); i++)
                    ~~^~~~~~~~~~~~
/in/foo.cc:19:11: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
         if(s[i] == ')')
           ^