With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Twitter is the mascot of San Francisco.
text_B: Flames is a 1926 American drama film directed by Lewis H. Moomaw and featuring Boris Karloff .. drama film. drama film. Boris Karloff. Boris Karloff. One reel of the feature survives at the Library of Congress .. Library of Congress. Library of Congress
not_related.