Input (grade 11): The ballet premiered on 25 May 1870 at the Théâtre Impérial de l ´ Opéra, with Giuseppina Bozzacchi in the principal role of Swanhilda.
Output (grade 6): The ballet was first performed in May 25, 1870 at the Théâtre Impérial de l ´ Opéra.