/in/foo.cc: In function 'void dfs1(int)':
/in/foo.cc:22:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(register int i=0;i<G[x].size();++i){
                       ~^~~~~~~~~~~~
/in/foo.cc: In function 'void dfs2(int)':
/in/foo.cc:52:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(register int i=0;i<G[x].size();++i){
                       ~^~~~~~~~~~~~
/in/foo.cc: In function 'void getfa(int)':
/in/foo.cc:79:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(register int i=0;i<G[x].size();++i){
                       ~^~~~~~~~~~~~