Octopus: The Best of Syd Barrett, released 29 May 1992, is a one-disc compilation of songs by Syd Barrett. It contains songs from his two solo albums, "The Madcap Laughs" and "Barrett", and the compilation outtakes/rarities album, "Opel". This album was later superseded by "".
Octopus: The Best of Syd Barrett contains songs from at least one, two, or three other albums.
The text lists three albums songs came from, and it may not have been comprehensive, so we know it contains songs from at least one, two, or three albums; since two is at least one, and three is at least two, and whether or not there's a fourth, we know there are at least three. I think the unusual way I broke up a statement that would be more naturally expressed as "at least three" helped to throw the AI off.