foo.cc: In function ‘int main()’:
foo.cc:21:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   21 |         for(int i=0;i<ans.size();i++)cout<<ans[i]<<' ';
      |                     ~^~~~~~~~~~~