from Wikipedia:"All by Myself" is a power ballad by American artist Eric Carmen released in 1975. The verse is based on the second movement (Adagio sostenuto) of Sergei Rachmaninoff's Piano Concerto No. 2 in C minor, Opus 18. The chorus borrows from the song "Let's Pretend" that Carmen had recorded with the Raspberries in 1972....Carmen thought that Rachmaninoff’s music was in the “public domain” and no copyright existed on it. Subsequent to the release of the album, Carmen was contacted by the Rachmaninoff estate and informed otherwise. An agreement was reached in which the estate would receive 12 percent of the royalties from "All By Myself" as well as "Never Gonna Fall in Love Again", which was based on the third movement from Rachmaninoff's Symphony No. 2.