/in/foo.cc: In function 'int main()':
/in/foo.cc:28:38: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   28 |     r.reserve(n + q->size()*(u.size()>m?u.size()-m:0));
      |                              ~~~~~~~~^~