/in/foo.cc: In function 'int main()':
/in/foo.cc:32:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<v[ans].size();i++) is[v[ans][i]]=1;
              ~^~~~~~~~~~~~~~
/in/foo.cc:33:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<v[ans].size();i++){
              ~^~~~~~~~~~~~~~