/in/foo.cc: In function 'std::vector<int> merge(const std::vector<int>&, const std::vector<int>&)':
/in/foo.cc:8:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 |     while (i < a.size() && j < b.size()) {
      |            ~~^~~~~~~~~~
/in/foo.cc:8:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 |     while (i < a.size() && j < b.size()) {
      |                            ~~^~~~~~~~~~
/in/foo.cc:12:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   12 |     while (i < a.size()) res.push_back(a[i++]);
      |            ~~^~~~~~~~~~
/in/foo.cc:13:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   13 |     while (j < b.size()) res.push_back(b[j++]);
      |            ~~^~~~~~~~~~