/in/foo.cc: In function 'std::string checkSequence(std::vector<int>)':
/in/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 = 2; i < cards.size(); i++) {
      |                     ~~^~~~~~~~~~~~~~