/in/foo.cc: In function 'bool judge(std::__cxx11::string)':
/in/foo.cc:190:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < s.size(); i++)
                     ~~^~~~~~~~~~
/in/foo.cc: In function 'std::__cxx11::string div(std::__cxx11::string, std::__cxx11::string, int)':
/in/foo.cc:187:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^