/in/foo.cc: In function 'void out()':
/in/foo.cc:27:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(register int j=0;j<G[i].size();++j)
                        ~^~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:52:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(register int i=0;i<G[x].size();++i){
                        ~^~~~~~~~~~~~