With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: FC Barcelona is operated by 20,000 of its supporters.
text_B: Langdeau Site is an archaeological site in Lyman County , South Dakota , near Lower Brule , South Dakota .. archaeological site. archaeological site. It was declared a National Historic Landmark in 1964 .. National Historic Landmark. National Historic Landmark. At the time of the designation in 1964 , it was stated  :. The exact location / address of this historic site is restricted .
not_related.