/in/foo.cc: In function 'void spfa(int)':
/in/foo.cc:25:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<e[u].size();i++)
                 ~^~~~~~~~~~~~
/in/foo.cc: In function 'void spfa1()':
/in/foo.cc:66:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i=0;i<e[u].size();i++)
                     ~^~~~~~~~~~~~