/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:13:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<G[u].size();i++)
                 ~^~~~~~~~~~~~
/in/foo.cc: In function 'void rdfs(int)':
/in/foo.cc:24:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<rG[u].size();i++)
                 ~^~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:50:31: error: 'memset' was not declared in this scope
     memset(book,0,sizeof(book));
                               ^
/in/foo.cc:55:32: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::vector<int>::size_type {aka long unsigned int}' [-Wformat=]
     printf("%d",cmp[cnt].size());
                                ^