/in/foo.cc: In member function 'void TOPO::sort_()':
/in/foo.cc:40:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int j=0;j<ed[i].size();j++)if(ans[ed[i][j]]==0)ans[ed[i][j]]=++cnt;
                 ~^~~~~~~~~~~~~