foo.cc: In member function 'void str::AC_automaton::insert(std::string)':
foo.cc:327:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  327 |         for (int i = 0; i < s.length(); i++) {
      |                         ~~^~~~~~~~~~~~
foo.cc: In member function 'int str::AC_automaton::query(std::string)':
foo.cc:353:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  353 |         for (int i = 0; i < s.length(); i++) {
      |                         ~~^~~~~~~~~~~~

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