/in/foo.cc: In function 'void dfs(int, std::vector<int>, int)':
/in/foo.cc:18:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i=0;i<q.size();i++){
                     ~^~~~~~~~~
/in/foo.cc: In function 'void spfa()':
/in/foo.cc:50:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int i=0;i<g[u].size();i++){
                         ~^~~~~~~~~~~~
/in/foo.cc:61:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                      for(int x=0;x<kk[u].size();x++){
                                  ~^~~~~~~~~~~~~
/in/foo.cc:78:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<w.size();i++){
                 ~^~~~~~~~~