foo.cc: In function 'int main()':
foo.cc:43:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |     for (int i = 0; i < a.size(); i ++, time ++ ) res += a[i] * time;
      |                     ~~^~~~~~~~~~
foo.cc:44:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |     for (int i = 0; i < b.size(); i ++, time ++ ) res += b[i] * time;
      |                     ~~^~~~~~~~~~
foo.cc:45:14: warning: format '%d' expects argument of type 'int', but argument 2 has type 'll' {aka 'long long int'} [-Wformat=]
   45 |     printf("%d", res);
      |             ~^   ~~~
      |              |   |
      |              int ll {aka long long int}
      |             %lld

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