/in/foo.cc: In member function 'std::vector<int> SeqList::Union(SeqList&) const':
/in/foo.cc:31:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < seq.size(); i++)
                   ~~^~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:55:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < merseq.size(); i++)
                   ~~^~~~~~~~~~~~~~~