foo.cc: In function 'std::vector<int> MergeSubs(std::vector<int>&)':
foo.cc:8:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 |     for (int i = 1; i < arr.size(); i++) {
      |                     ~~^~~~~~~~~~~~
foo.cc:18:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |     for (int i = 0; i < sorted_subs.size(); i++) {
      |                     ~~^~~~~~~~~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:42:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   42 |     for (int i = 0; i < merged_a1.size(); i++) {
      |                     ~~^~~~~~~~~~~~~~~~~~
foo.cc:46:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |     for (int i = 0; i < merged_a2.size(); i++) {
      |                     ~~^~~~~~~~~~~~~~~~~~

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