foo.cc: In function 'VI sub(VI&, VI&)':
foo.cc:20:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |         if (i < b.size()) t -= b[i];
      |             ~~^~~~~~~~~~
foo.cc: In function 'VI add(VI&, VI&)':
foo.cc:32:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   32 |         if (i < a.size()) t += a[i];
      |             ~~^~~~~~~~~~
foo.cc:33:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   33 |         if (i < b.size()) t += b[i];
      |             ~~^~~~~~~~~~

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