With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Oh Yeon-seo worked in a K-pop girl group.
text_B: The Gravensteen is a castle in Ghent originating from the Middle Ages .. Ghent. Ghent. Middle Ages. Middle Ages. The name means `` castle of the counts '' in Dutch .. Dutch. Dutch language. The Gravensteen is situated at an altitude of 9 meters .
not_related.