foo.cc: In function 'int main()':
foo.cc:10:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |                 for(int j=0;j<a.size();j++){
      |                             ~^~~~~~~~~
foo.cc:21:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |         for(int i=0;i<a.size();i++){
      |                     ~^~~~~~~~~

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