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'.

Example Input: Sentence 1:However , 2 + ions ( Be ) or even 1 + ( Li ) show some polarizing power because their sizes are so small . Sentence 2:nan
Example Output: SINGLE_CONN_INNER_ANAPHORA

Example Input: Sentence 1:In 1905 he bought the yearling Poseidon , which subsequently won the Australian Jockey Club Derby and St Leger , the Victoria Derby and the Melbourne Cup and the Caulfield Cup twice . Sentence 2:nan
Example Output: SINGLE_RELATIVE

Example Input: Sentence 1:Aaliyah originally recorded the song for her 1996 album One in a Million , but it was completed after the album had finished post-production , and she chose to save it for her next album . Sentence 2:nan
Example Output:
SINGLE_S_COORD_ANAPHORA