/in/foo.cc: In function 'll FAKEDFS(Graph&, int)':
/in/foo.cc:64:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'void output()':
/in/foo.cc:109:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=1;j<block[i].size();j++)
               ~^~~~~~~~~~~~~~~~
/in/foo.cc: In function 'void buildtree(int)':
/in/foo.cc:79:9: warning: 'rt' may be used uninitialized in this function [-Wmaybe-uninitialized]
  FAKEDFS(tree[t],rt);
  ~~~~~~~^~~~~~~~~~~~