/in/foo.cc: In function 'void spfa(int)':
/in/foo.cc:16:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<e[u].size();++i){
               ~^~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:60:38: warning: 'ed' may be used uninitialized in this function [-Wmaybe-uninitialized]
  if(dis[ed]!=0x3f3f3f3f) cout<<cnt[ed];
                                      ^
/in/foo.cc:59:10: warning: 'st' may be used uninitialized in this function [-Wmaybe-uninitialized]
  spfa(st);
          ^