System Overflow Exception : i´m new here, i hope you can help me, and sorry for my bad english :D

I tried to save the MaximumApplicationAddress from SystemInfo into an uint.
But i got an error (System Overflow Exception). 
I tried alot and also googled alot, but nothing helps. If i convert or if i use an decimal, nothing helped.

Here is my source, hope you can help me and find the error :)

[Source][1]

I also maked an Screenshot from the error.

[Screenshot][2]

    Hope you can help me


  [1]: https://pastebin.com/nzR7g9UD
  [2]: https://i.stack.imgur.com/9qkoU.png