foo.cc: In function ‘int main()’:
foo.cc:33:28: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   33 |         for (int i = 0 ; i < va.size() ; i ++) {
      |                          ~~^~~~~~~~~~~
foo.cc:39:27: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   39 |         for (int i = 0; i < vc.size(); i ++)
      |                         ~~^~~~~~~~~~~