foo.cc: In function ‘int main()’:
foo.cc:17:18: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   17 |     for(int i=0;i<prime.size();i++) cout<<prime[i]<<" ";
      |                 ~^~~~~~~~~~~~~