Input (grade 12): In Greek mythology, Helenus (á 1\/4 Î "Î Î 1\/2 Î Ï) was the son of King Priam and Queen Hecuba of Troy, and the twin brother of the prophetess Cassandra.
Output (grade 4): Helenus was the son of King Priam and Queen Hecuba of Troy. His twin sister was Cassandra.