/in/foo.cc: In function 'void dfs(long long int)':
/in/foo.cc:13:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(ll i=0,v;i<es[u].size();i++){
                  ~^~~~~~~~~~~~~
/in/foo.cc: In function 'void sum(long long int)':
/in/foo.cc:30:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(ll i=0;i<es[u].size();i++) 
                ~^~~~~~~~~~~~~