sinterface Decolorizer {
  int toGrayScale(int rgb);
  
  sclass Red is Decolorizer {
    public int toGrayScale(int rgb) { ret (rgb >> 16) & 0xFF; }
  }
  
  sclass Green is Decolorizer {
    public int toGrayScale(int rgb) { ret (rgb >> 8) & 0xFF; }
  }
  
  sclass Blue is Decolorizer {
    public int toGrayScale(int rgb) { ret rgb & 0xFF; }
  }
  
  sclass Alpha is Decolorizer {
    public int toGrayScale(int rgb) { ret (rgb >> 24) & 0xFF; }
  }
}