最适合在离线应用程序中包含大量图像，视频和PDF的方法

I need to develop an offline application in which it has got around 700 images, around 100 videos, 100 pdf's need to be included along with apk.Currently i have put images in drawable folder,videos in raw folder, and pdf in asset folder.When i build the application including all this apk size goes upto 1.5gb.My question is 1.Is it appropriate to include images and video in res folder?Is there any other method to handle this situation 3.One peculiar error will get generated when you build the app that is "package r does not exist android studio".Even though apk gets generated,studio shows this errorI need to develop an offline application in whi