foo.cc: In function 'std::vector<int> add(std::vector<int>&, std::vector<int>&)':
foo.cc:12:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   12 |     for (int i = 0; i < A.size(); i ++ )
      |                     ~~^~~~~~~~~~
foo.cc:15:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |         if (i < B.size()) t += B[i];
      |             ~~^~~~~~~~~~

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