/in/foo.cc: In function 'void spfa()':
/in/foo.cc:22:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<e1[now].size();i++){
               ~^~~~~~~~~~~~~~~
/in/foo.cc:27:23: warning: value computed is not used [-Wunused-value]
      flag3[e1[now][i]]==1;
      ~~~~~~~~~~~~~~~~~^~~
/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:36:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<e2[pos].size() ;i++){
              ~^~~~~~~~~~~~~~~
/in/foo.cc: In function 'void bfs()':
/in/foo.cc:43:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<e1[i].size() ;j++){
               ~^~~~~~~~~~~~~