/in/foo.cc: In function 'void getprimes2(int, std::vector<int>&)':
/in/foo.cc:11:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   11 |                 for(int j=0;j<primes.size()&&i*primes[j]<=n;j++)
      |                             ~^~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:23:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   23 |         for(int i=0;i<primes.size()&&primes[i]<a;i++)x++;
      |                     ~^~~~~~~~~~~~~~