vector<string> split(string s, char delimiter) {
  vector<string> r;
  while (true) {
    string::size_type l = s.find(delimiter);
    if (l == string::npos) {
      r.push_back(s);
      break;
    }
    r.push_back(s.substr(0, l));
    s.erase(0, l + 1);
  }
  return r;
}