/in/foo.cc: In function 'void spfa()':
/in/foo.cc:25:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int i=0;i<g[u].size();i++){
                         ~^~~~~~~~~~~~
/in/foo.cc:31:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                      for(int x=0;x<kk[u].size();x++){
                                  ~^~~~~~~~~~~~~
/in/foo.cc:45:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<kk[m+1].size();i++){
                 ~^~~~~~~~~~~~~~~