/in/foo.cc: In member function 'bool MCMF::SPFA(int, int, int&, int&)':
/in/foo.cc:60:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int i=0;i<G[u].size();i++)
                         ~^~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:115:6: warning: unused variable 'cnt' [-Wunused-variable]
  int cnt=0;
      ^~~