With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Blackhat stars Diego Luna.
text_B: Heinrich von Staden -LRB- born 1939 -RRB- is a South African historian and classical scholar who has written several books and hundreds of articles and encyclopedia entries on ancient medicine , ancient philosophy , the history of science , and comparative literature .. South African. South African. He is one of the world 's foremost authorities on ancient science and medicine and has contributed to the transformation of the history of the subject in the period from the fifth century B.C. to the fifth century A.D. His monumental book Herophilus  : The Art of Medicine in Early Alexandria is considered the standard in the field .
not_related.