Input (grade 10): Das Rheingold ("The Rhine Gold") is the first of the four operas that comprise Der Ring des Nibelungen (The Ring of the Nibelung), by Richard Wagner.
Output (grade 6): Das Rheingold (The Rhinegold) is an opera by Richard Wagner. It is the first of the four operas that together tell a story called Der Ring des Nibelungen (The Ring of the Nibelung).