Question: Which ballet piece,  now one of the most popular of all ballets despite its initial failure, inspired "Somewhere" the song from the 1957 Broadway musical "West Side Story?"
Sentence (from "Somewhere (song)"): The music is composed by Leonard Bernstein with lyrics by Stephen Sondheim, and takes a phrase from the slow movement of Beethoven's 'Emperor' Piano Concerto, which forms the start of the melody, and also a longer phrase from the main theme of Pyotr Tchaikovsky's Swan Lake.
Relevant evidence: Yes