/in/foo.cc: In function 'void spfa(int)':
/in/foo.cc:36:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(register int i=0;i<b[u].size();i++){
                              ~^~~~~~~~~~~~
/in/foo.cc: In function 'void A_star(int)':
/in/foo.cc:60:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(register int i=0;i<a[u].size();i++){
                              ~^~~~~~~~~~~~