Is there a way to easily understand the CUDA Mergesort sample code?

Hi i am a Korean student studying CUDA. I am trying to study with CUDA Sort sample, but when I run the CUDA sample as it is, there are too many functions and there is no display (<<< >>>) in the main function so I can’t run it as it is. It’s a little hard. I wonder if there is a way to get a comment or a detailed explanation to make it easier to understand.