foo.cc: In function 'void Output(std::vector<int>&)':
foo.cc:14:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   14 |         for(int i=0; i<a.size(); i++)
      |                      ~^~~~~~~~~
foo.cc: In function 'void Solve(std::vector<Node>&, std::vector<int>&)':
foo.cc:21:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Node>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |         for(int i=0; i<a.size(); i++)
      |                      ~^~~~~~~~~

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