/in/foo.cc: In function 'void prime_sift()':
/in/foo.cc:27:13: warning: unused variable 'tmp_sum' [-Wunused-variable]
   27 |         int tmp_sum,a,b,c,d,e;
      |             ^~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:131:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::__cxx11::basic_string<char> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  131 |         for(int i=0;i<ans.size();i++)
      |                     ~^~~~~~~~~~~