With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: The Chernobyl disaster was an accident.
text_B: Ngagu is a village on the Zanzibari island of Pemba .. Pemba. Pemba Island. It is located at the end of a narrow peninsula known as Ras Mkumbuu , which lies on the west coast immediately to the north of Chake-Chake Bay .. Ras Mkumbuu. Ras Mkumbuu. Chake-Chake Bay. Chake-Chake Bay. The town is located close to the Quanbalu Ruins .. Quanbalu Ruins. Quanbalu Ruins. Possibly dating from as early as the eighth century , these are the remains of a major trading centre which may have been Africa 's oldest Muslim town .
not_related.