In this task, you are given two sentences in the English language and your task is to classify them into one of their discourse types. A discourse type is an indicator to classify the given two sentences on the basis of a co-text as well as a relevant context. There are 13 discourse types in total which are 'SINGLE_S_COORD', 'SINGLE_CATAPHORA', 'SINGLE_CONN_INNER', 'SINGLE_APPOSITION', 'SINGLE_VP_COORD', 'SINGLE_CONN_START', 'PAIR_ANAPHORA', 'PAIR_CONN', 'SINGLE_RELATIVE', 'SINGLE_CONN_INNER_ANAPHORA', 'SINGLE_S_COORD_ANAPHORA', 'PAIR_CONN_ANAPHORA' and 'PAIR_NONE'.
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Question: Sentence 1:The Confederate force , which actually numbered about 4,000 men , was led by Col. Lawrence O'Bryan Branch . Sentence 2:nan

Answer: SINGLE_RELATIVE


Question: Sentence 1:After gathering information from the public , the mystery man was revealed to be Kisaburo Sasamoto , a physicist and former college mate of Rinna , as well as her boyfriend back in America . Sentence 2:However , his whereabouts were unknown after he graduated .

Answer: PAIR_CONN_ANAPHORA


Question: Sentence 1:Although the functions of teahouses vary widely in different countries , teahouses often serve as centers of social interaction , like coffeehouses . Sentence 2:nan

Answer:
SINGLE_CONN_START