foo.cc: In function 'int main()':
foo.cc:15:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |  for(int i = 0; i < v.size() - 1; i ++){
      |                 ~~^~~~~~~~~~~~~~
foo.cc:16:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   16 |   for(int j = i + 1; j < v.size(); j ++){
      |                      ~~^~~~~~~~~~
foo.cc:20:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |  for(int i = 0; i < v.size(); i ++){
      |                 ~~^~~~~~~~~~

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