/in/foo.cc: In function 'int judge(std::__cxx11::string)':
/in/foo.cc:6:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<s.size()-3;i++)
                 ~^~~~~~~~~~~
/in/foo.cc:8:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=i+1;j<s.size()-2;j++)
                       ~^~~~~~~~~~~
/in/foo.cc:10:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int k=j+1;k<s.size()-1;k++)
                           ~^~~~~~~~~~~
/in/foo.cc:12:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                 for(int l=k+1;l<s.size();l++)
                               ~^~~~~~~~~