/in/foo.cc: In function 'void DFS1(int, int)':
/in/foo.cc:26:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(re int i=0;i<a[p].to.size();++i)
                 ~^~~~~~~~~~~~~~~
/in/foo.cc: In function 'void DFS2(int, int)':
/in/foo.cc:38:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(re int i=0;i<a[p].to.size();++i)
                 ~^~~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:66:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(f<a[t].s.size()) printf("%d\n",lastans=a[t].s[f]);
       ~^~~~~~~~~~~~~~
/in/foo.cc:68:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   else if(-f<a[t].f.size()) printf("%d\n",lastans=a[t].f[-f]);
           ~~^~~~~~~~~~~~~~