foo.cc: In member function 'void Persons::print()':
foo.cc:65:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Person*>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   65 |   for (int i = 0; i < Ps.size(); i++)
      |                   ~~^~~~~~~~~~~
foo.cc: In destructor 'Persons::~Persons()':
foo.cc:71:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Person*>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   71 |   for (int i = 0; i < Ps.size(); i++)
      |                   ~~^~~~~~~~~~~

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