I was so stupid to download and install the public beta of Yosemite on my main drive, overwriting Mavericks.. I thought that it was easy to go back to mavericks after testing it a little. Can anyone please tell me how i can install Mavericks again? I don't have any TimeMachine backups, all my stuff is on external drives. I have tried cmd+r when booting to get to the installer, but i can only install Yosemite again.