/in/foo.cc: In function 'void MAXTree(int)':
/in/foo.cc:40:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<E[root].size();i++)
              ~^~~~~~~~~~~~~~~
/in/foo.cc:56:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<E[now].size();i++)
               ~^~~~~~~~~~~~~~
/in/foo.cc:50:28: warning: 'next' may be used uninitialized in this function [-Wmaybe-uninitialized]
   tree[next].dep=tree[now].dep+1;
                  ~~~~~~~~~~^~~