class Raindrops {
  String convert(int factor) {
    final StringBuffer result = StringBuffer();
    if (factor % 3 == 0) result.write('Pling');
    if (factor % 5 == 0) result.write('Plang');
    if (factor % 7 == 0) result.write('Plong');
    return (result.isEmpty) ? factor.toString() : result.toString();
  }
}