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:As a result of the shortages , Venezuelans must search for food , wait in lines for hours and sometimes settle without having certain products . Sentence 2:nan

Answer: SINGLE_VP_COORD


Question: Sentence 1:The Tweedmouth junction faced south , so that Berwick to Kelso trains had to reverse there . Sentence 2:nan

Answer: SINGLE_CONN_INNER


Question: Sentence 1:A recurring theme was his belief that abstract concepts can be grasped by young people , which he preached in his 1936 book , An Invitation to Mathematics . Sentence 2:nan

Answer:
SINGLE_RELATIVE