/in/foo.cc: In member function 'bool Dinic::bfs()':
/in/foo.cc:46:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int i=0;i<G[x].size();i++)
                         ~^~~~~~~~~~~~
/in/foo.cc: In member function 'int Dinic::dfs(int, int)':
/in/foo.cc:65:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int&i=cur[x];i<G[x].size();i++)//从上次考虑的弧开始，注意要使用引用，同时修改cur[x]
                          ~^~~~~~~~~~~~