[xubuntu] Installing some programs and games

Hello

Im trying to install some programs like R with the (terminal) but i get 404 error.

im adding PPA (and try to get sudo apt-get update) but it fails to download and get multiple errors.

does not have a Release file., W data from such a repository can't be authenticated and is therefore potentially dangerous to use., W:See apt-secure(8) manpage for repository creation and user configuration details.

Its like this problem http://askubuntu.com/questions/75936...adding-problem

Sorry for my English

Nahtal

PS.

W:The repository 'http://ppa.launchpad.net/hikariknight/unix-r-client/ubuntu xenial Release' does not have a Release file., data from such a repository can't be authenticated and is therefore potentially dangerous to use., W:See apt-secure(8) manpage for repository creation and user configuration details., E:Failed to fetch http://ppa.launchpad.net/hikariknigh...amd64/Packages 404 Not Found, E:Failed to fetch http://ppa.launchpad.net/hikariknigh...-i386/Packages 404 Not Found, E:Some index files failed to download. They have been ignored, or old ones used instead.