foo.cc: In function 'int main()':
foo.cc:18:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |     for(int i = 0; i < stu.size(); ++i){
      |                    ~~^~~~~~~~~~~~
foo.cc:24:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |     for(int i = 0; i < stu.size(); i++){
      |                    ~~^~~~~~~~~~~~

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