/in/foo.cc: In function 'void dfs2(int)':
/in/foo.cc:42:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(i=0;i<qry[u].size();++i)ans[qp[u][i]]=sum(dfl[qry[u][i]])-sum(dfn[qry[u][i]]-1);
          ~^~~~~~~~~~~~~~