foo.cc: In member function 'int SeqList::Search(int)':
foo.cc:14:27: 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 < seq.size(); i++) {
      |                         ~~^~~~~~~~~~~~
foo.cc: In member function 'void SeqList::SearchRemove(int)':
foo.cc:24:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |             for (int i = k; i < seq.size() - 1; i++) {
      |                             ~~^~~~~~~~~~~~~~~~
foo.cc: In member function 'std::vector<int> SeqList::Union(SeqList&)':
foo.cc:36:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   36 |         for (int i = 0; i < obj.seq.size(); i++) {
      |                         ~~^~~~~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:60:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   60 |     for (int i = 0; i < res.size(); i++) {
      |                     ~~^~~~~~~~~~~~