/in/foo.cc: In function 'bool bfs()':
/in/foo.cc:25:16: 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 dfs(int, int)':
/in/foo.cc:37:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int &i=cur[u];i<g[u].size();i++){
                    ~^~~~~~~~~~~~